1.The larger of two numbers is 1 more than twice the smaller.The sum of the numbers is 20 less that three times the larger.Find the numbers.2.The price of a sweater is $5 less than twice the price of a shirt.If four sweaters and three shirts cost $20
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1.The larger of two numbers is 1 more than twice the smaller.The sum of the numbers is 20 less that three times the larger.Find the numbers.2.The price of a sweater is $5 less than twice the price of a shirt.If four sweaters and three shirts cost $20
1.The larger of two numbers is 1 more than twice the smaller.The sum of the numbers is 20 less that three times the larger.Find the numbers.
2.The price of a sweater is $5 less than twice the price of a shirt.If four sweaters and three shirts cost $200,find the price of each shirt and each sweater.
3.A shipment of TV sets,some weighing 30kg each and the others weighing 50kg each,has a total weight of 880kg.If there are 20 TV sets all together,how many weigh 50kg?
4.A scholarship fund raised $7000 in contributions.Part was invested in bonds paying 6% interest,and the rest was invested in bank certificates paying 8.5%,If the total annual income is $520,find the amout invested at each rate.
5.Dr.D.Jones has a total of $3000 invested in two stocks.Stock A pays dividends at the rate of 6% and Stock B at the rate of 8%.If her dividends from the two stocks total $220 per year,how much did she invest in each stock?
6.A boat travels 60km upstream(against the current) in 5 hours.The boat travels the same distance downstream in 3 hours.What is the rate of the boat in still water?What is the rate of the current?
7.On an upstream trip,a canoe travels 40km in 5hours.Downstream,it travels the same distance in half the time.What is the rate of the canoe in still water and the rate of the current?
8.When a plane flies with the wind,it can travel the same distance in 5hours.Find the rate of the plane in still air and the rate of the wind.
9.A duck can fly 2400m in 10min with the wind.Against the wind,it can fly only two thirds of this distance in 10min.How fast could the duck fly in still air?What is the rate of the wind?
10.When lucy swims with the current,she swims 18km in 2hours.Against the current,she can swim only 14km in the same time.How fast can lucy swim in still water?What is the rate of the current?
11.With the wind,a plane flew 1400km in 4 hours.On the return trip,the pilot was forced to land after 1h 30min,having traveled only 450km.Find the rate of the plane in still air and the rate of the wind.
12.With the wind,a jet can fly 2500km in 2h 30min.Against the wind,it can fly only 2000km in the same time.Find the rate of the jet in still air and the rate of the wind.
13.A salmon swims 100m in 8 min downstream.Upstream,it would take the fish 20min to swim the same distance.What is the rate of the salmon in still water?What is the rate of the current?
这12题我都有答案,你们帮我写式子就行了,记住要用2个未知数来代表,
1.13,6
2.sweater:$35,shirt:$20
3.14
4.3000-6%,4000-8.5%
5.Stock A-1000,Stock B-2000
6.Boat-16,current-4
7.12,4
8.550-plane,50-wind
9.duck-200meter/min,wind-40
10.8,current:1
11.325-plane,25-wind
12.jet-900,wind-100
13.salmon-8.75,current-3.75
1.The larger of two numbers is 1 more than twice the smaller.The sum of the numbers is 20 less that three times the larger.Find the numbers.2.The price of a sweater is $5 less than twice the price of a shirt.If four sweaters and three shirts cost $20
1.The larger of two numbers is 1 more than twice the smaller.The sum of the numbers is 20 less that three times the larger.Find the numbers.
1.两个数字种较大的那个是较小那个的两倍还多1.这两个数之和比较大数的3倍少20.求这两个数.
设较大数为x,较小数为y
x=2y+1,x+y=3x-20
解得x=13 y=6
2.The price of a sweater is $5 less than twice the price of a shirt.If four sweaters and three shirts cost $200,find the price of each shirt and each sweater.
2.一件毛衣的价格比一件衬衫价格的两倍少5块钱.如果4件毛衣和3件衬衫一共200块,求每件毛衣和衬衫的价格.
设毛衣价格x,衬衫价格y
x=2y-5,4x+3y=200
解得x=35 y=20
3.A shipment of TV sets,some weighing 30kg each and the others weighing 50kg each,has a total weight of 880kg.If there are 20 TV sets all together,how many weigh 50kg?
3.运送一批电视,有的每台重30KG,其他的每台重50KG,这批电视的总重量是880KG.如果一共有20台电视,其中有多少台重50KG?
设X台重30KG的,Y台重50KG的
30x+50y=880,x+y=20
解得x=6 y=14
4.A scholarship fund raised $7000 in contributions.Part was invested in bonds paying 6% interest,and the rest was invested in bank certificates paying 8.5%,If the total annual income is $520,find the amout invested at each rate.
4.一项基金总共募集到7000元.一部分投资于可获得6%利息的债券,其他投资于利息8%的bank certificates.如果总共的年收入为520元,求每一项的投资额.
设债券投资x元,bank certificates投资y元
x+y=7000,0.06x+0.085y=520
解得x=3000 y=4000
5.Dr.D.Jones has a total of $3000 invested in two stocks.Stock A pays dividends at the rate of 6% and Stock B at the rate of 8%.If her dividends from the two stocks total $220 per year,how much did she invest in each stock?
琼斯医生总共投资3000元在两只股票上.股票A分红为6%,股票比分红为8%.如果她每年获得的总分红为220元,她在每只股票上的投资额是多少?
设股票A投资x元,股票B投资y元
x+y=3000
0.06x+0.08y=220
6.A boat travels 60km upstream(against the current) in 5 hours.The boat travels the same distance downstream in 3 hours.What is the rate of the boat in still water?What is the rate of the current?
6.一条船以60KM逆水行驶5小时.同样的距离顺水行驶只需要3小时.求船在静水中的速度和水速.
设船静水速度为x,水速为y
x-y=60,(x+y)*3=60*5
7.On an upstream trip,a canoe travels 40km in 5hours.Downstream,it travels the same distance in half the time.What is the rate of the canoe in still water and the rate of the current?
7.逆水航行,独木舟以40km行驶了5小时.顺水航行相同的距离只用了一半的时间.求独木舟在静水种的速度和水速.
设船在静水中速度x,水速为y
x-y=40,(x+y)*(5/2)=40*5
8.When a plane flies with the wind,it can travel the same distance in 5hours.Find the rate of the plane in still air and the rate of the wind.
8.题目不全啊
9.A duck can fly 2400m in 10min with the wind.Against the wind,it can fly only two thirds of this distance in 10min.How fast could the duck fly in still air?What is the rate of the wind?
9.一只鸭子顺风飞2400m需要10分钟,逆风的时候10分钟只能飞2/3的距离.鸭子无风飞行速度多少?风速多少?
设鸭子无风飞行速度x,风速y
(x+y)*10=2400
(x-y)*10=2400*2/3
10.When lucy swims with the current,she swims 18km in 2hours.Against the current,she can swim only 14km in the same time.How fast can lucy swim in still water?What is the rate of the current?
10.Lucy顺水游18km需要2小时,逆水相同的时间内只能游14km.求lucy静水中的速度和水速
设lucy静水中的速度x,水速y
(x+y)*2=18
(x-y)*2=14
11.With the wind,a plane flew 1400km in 4 hours.On the return trip,the pilot was forced to land after 1h 30min,having traveled only 450km.Find the rate of the plane in still air and the rate of the wind.
11.飞机顺风飞1400km需要4小时,返航时,飞行员在1小时30分之后迫降,只飞了450km.求飞机无风时的速度和风速
12.With the wind,a jet can fly 2500km in 2h 30min.Against the wind,it can fly only 2000km in the same time.Find the rate of the jet in still air and the rate of the wind.
13.A salmon swims 100m in 8 min downstream.Upstream,it would take the fish 20min to swim the same distance.What is the rate of the salmon in still water?What is the rate of the current?
这12题我都有答案,你们帮我写式子就行了,记住要用2个未知数来代表,
答案:
1.13,6
2.sweater:$35,shirt:$20
3.14
4.3000-6%,4000-8.5%
5.Stock A-1000,Stock B-2000
6.Boat-16,current-4
7.12,4
8.550-plane,50-wind
9.duck-200meter/min,wind-40
10.8,current:1
11.325-plane,25-wind
12.jet-900,wind-100
13.salmon-8.75,current-3.75
1.列方程 2a+1=b a+b+20=3b a为较小的数。
2.同理 2X+5=Y 3X+4Y=200 X为shirt
3.30X+50Y=880 X+Y=20 Y求出来就是50Kg的
4.6%X+8.5%Y=520 X+Y=7000
5.和4没什么区别,就是数据不同
不想做了 都是一样的道理,,列方程就好 关键是你看懂了 肯定会做的