1/4 + 2/5 = 5/20 + 8/20 = 13/20
5/7 - 1/6 = 30/42 - 7/42 = 23/42
23/40 - 3/8 = 46/80 - 30/80 = 16/80 = 1/5
1/4 + 2/5 = 5/20 + 8/20 = 13/20
5/7 - 1/6 = 30/42 - 7/42 = 23/42
23/40 - 3/8 = 46/80 - 30/80 = 16/80 = 1/5