Đáp án:+Giải thích các bước giải:

 `A=4/7.31 +6/7.41 +9/10.41 + 7/10.57`

`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)`

`B=7/19.31 + 5/19.43 + 3/23.43+11/23.57`

`B=2(7/31.38 + 5/38.43 +3/43.46+11/46.57)`

`B=2(1/31-1/38+1/38-1/43+1/43-1/46+1/46-1/57)`

`B=2(1/31-1/57)`

`A/B=(5(1/31-1/57))/(2(1/31-1/57))=5/2`

Vậy `A/B=5/2`