1/5 - 1/6 = 6/30 - 5/30 = 1/30
3/4 - 1/3 = 9/12 - 4/12 = 5/12
7/9 - 2/11 = 77/99 - 18/99 = 59/99
3/4 - 4/9 = 27/36 - 16/36 = 11/36
7/8 - 5/12 = 63/84 - 35/84 = 28/84 = 1/3
11/12 - 11/18 = 99/108 - 66/108 = 33/108 = 11/36.
1/5 - 1/6 = 6/30 - 5/30 = 1/30
3/4 - 1/3 = 9/12 - 4/12 = 5/12
7/9 - 2/11 = 77/99 - 18/99 = 59/99
3/4 - 4/9 = 27/36 - 16/36 = 11/36
7/8 - 5/12 = 63/84 - 35/84 = 28/84 = 1/3
11/12 - 11/18 = 99/108 - 66/108 = 33/108 = 11/36.