有分别写有数字9和5的卡片个若干张,甲、乙两人从中分别各取出9张,甲取得写有数字9的卡片张数与乙取得写有数字5的卡片张数恰好相同,甲所取9张卡片的数字比乙所取卡片上的数字和多20.那
来源:学生作业帮助网 编辑:作业帮 时间:2024/10/04 20:39:44
有分别写有数字9和5的卡片个若干张,甲、乙两人从中分别各取出9张,甲取得写有数字9的卡片张数与乙取得写有数字5的卡片张数恰好相同,甲所取9张卡片的数字比乙所取卡片上的数字和多20.那
有分别写有数字9和5的卡片个若干张,甲、乙两人从中分别各取出9张,
甲取得写有数字9的卡片张数与乙取得写有数字5的卡片张数恰好相同,甲所取9张卡片的数字比乙所取卡片上的数字和多20.那么乙所取9张卡片上的数字之和是多少
有分别写有数字9和5的卡片个若干张,甲、乙两人从中分别各取出9张,甲取得写有数字9的卡片张数与乙取得写有数字5的卡片张数恰好相同,甲所取9张卡片的数字比乙所取卡片上的数字和多20.那
设甲取得数字9的卡片张数是X 9X+5*(9-X)-20=5X+9*(9-X)解得X=7
那么乙的数字和是5*7+9*2=53
53
设甲取到x张9,则:
9x+5(9-x)=5x+9(9-x)+20
解得:x=7
所以乙取得数之和为5x+9(9-x)=53
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