3/8 - 1/7 11/80 - 11/90 3/5 - 4/9 6 - 2 13/18 23/25 - 11/15 8 1/8 - 3 1/9

13/56
11/720
7/45
59/18
14/75

3/8-1/7=21/56-8/56=13/56
11/80-11/90=990/7200-880/7200=100/7200
3/5-4/9=27/45-20/45=7/45
6-2 13/18= 5 18/18 - 2 13/18=3 5/18
23/25-11/15=69/75 - 55/75 =14/75
8 1/8 - 3 1/9=8 9/72 - 9 8/72=1 1/72