(1+1/6):(3/8-1/4)=9 1/3

1. 1+1/6= 1 1/6

2. 3/8-1/4=3/8-2/8=1/8

3. 1 1/6:1/8=7/6:1/8=7/6*8/1=7/3*4/1=28/3=9 1/3

(5/7-2/3):(4/9-5/12)=1 5/7

1. 5/7-2/3=15/21-14/21=1/21

2. 4/9-5/12=16/36-15/36=1/36

3.1/21:1/36=1/21*36/1=12/7=1 5/7