1/2:1/3=1/2*3/1=3/2 3/2*1/3=3/6=1/2
2/5:5/6=2/5*6/5=12/25 12/25*5/6=2/5
4/9:8/9 =4/9*9/8=1/2 1/2*8/9=8/18=4/9
7/30:14/15=7/30*15/14=1/4 1/4*14/15=14/60=7/30
5/42:4/21=5/42*21/4=5/8 5/8*4/21=5/42
16/25:64/75=16/25*75/64=3/4 3/4*64/75=16/25
100/111:50/81=100/111*81/50=54/37 54/37*50/81=300/333=100/111
52/81:26/27 =52/81*27/26=2/3 2/3*26/27=52/81