5%x+40%(140-x)=30%×140zen me zuo ne?yao wan zheng de suan shi

5%x+40%(140-x)=30%×140zen me zuo ne?yao wan zheng de suan shi
5%x+40%(140-x)=30%×140
zen me zuo ne?yao wan zheng de suan shi

5%x+40%(140-x)=30%×140zen me zuo ne?yao wan zheng de suan shi
5%x+40%(140-x)=30%×140
5x+40(140-x)=30×140
除以5得
x+8(140-x)=6×140
x+1120-8x=840
x-8x=840-1120
-7x=-280
x=280÷7
x=40