1/2-1/7=7/14-2/14=5/14
2/3-1/4=8/12-3/12=5/12
5/4-1/2=5/4-2/4=3/4
5/6-1/3=5/6-2/6=3/6=1/3
7/2-1/5=35/10-2/10=33/10
1-2/5=5/5-2/5=3/5
2/5-1/2=4/10-5/10=-1/10
11/4-3/2=11/4-6/4=5/4
7/6-3/4=14/12-9/12=5/12
11/12-5/18=33/36-10/36=23/36
13/20-7/30=39/60-14/60=25/60=5/12
37/45-17/30=74/90-61/90=13/90