Đáp án:
`130/1767`
Giải thích các bước giải:
`A=4/7.31+6/7.41+9/10.41+7/10.57`
`A=(4.5)/(5.7.31)+(6.5)/(5.7.41)+(9.5)/(5.10.41)+(7.5)/(5.10.57)`
`A=20/31.35+30/35.41+45/41.50+35/50.57`
`A/5=4/31.35+6/35.41+9/41.50+7/50.57`
`A/5=1/31-1/35+1/35-1/41+1/41-1/50+1/50-1/57`
`A/5=1/31-1/57`
`A/5=26/1767`
`A=26/1767*5`
`A=130/1767`
Vậy `A=130/1767`.