4/5 - 12/5-8/5
7/10 - 3/10+4/10
9/6 - 4/6+5/6
15/12 - 3/4×5/3
2 - 3/2÷3/4
7 - 7/5÷1/5
15/24 - 3/8×5/3
3 - 9/2÷3/2
6/15 - 2/3÷5/3