百珊
幼苗
共回答了22个问题采纳率:100% 举报
1.(1/2-9)X1/5=X-9
x=9+1/10-9/5
x=7又3/10
2.1/19x+(1540-x)x1/10=100
10x+(1540-x)x19=100x190
10x+1540x19-19x=100x190
9x=(1540-1000)x19
x=1140
3.3/5x X18+2/5x X(18-10)=2870
3/5x X18+2/5x X18-4x=2870
(3/5+2/5)x X18-4x=2870
18x-4x=2870
14x=2870
x=205
1年前
1