1/3 - 1/9 = 3/9 - 1/9 = 2/910/21 - 1/3 = 10/21 - 7/21 = 3/21 = 1/714/15 - 3/5 = 14/15 - 9/15 = 5/15 = 1/317/18 - 1/9 = 17/18 - 2/18 = 15/18 = 5/64/9 - 13/45 = 20/45 - 13/45 = 7/451/3 - 7/30 = 10/30 - 7/30 = 3/30 = 1/10
1/3 - 1/9 = 3/9 - 1/9 = 2/9
10/21 - 1/3 = 10/21 - 7/21 = 3/21 = 1/7
14/15 - 3/5 = 14/15 - 9/15 = 5/15 = 1/3
17/18 - 1/9 = 17/18 - 2/18 = 15/18 = 5/6
4/9 - 13/45 = 20/45 - 13/45 = 7/45
1/3 - 7/30 = 10/30 - 7/30 = 3/30 = 1/10