8/15 - 4/9 = 8/5 - 4/3 = 24/15 - 20/15 = 4/15
3 13/15 + 6 7/10 = 3 13/3 + 6 7/2 = 22/3 + 19/2 = 44/6 + 57/6 = 101/6 = 96 5/6
6 - 1 3/5 = 30/5 - 8/5 = 22/5 = 4 2/5
4 2/7 - 1 4/9 = 30/7 - 13/9 = 270/63 - 91/63 = 207/63 = 69/21 = 3 6/21
4,62 - 3 11/20 = 46,2 - 3 11/2 = 72,4/2 - 17/2 = 55,4/2 = 27,7