81/5- 3 2/7 5 6/13 -2 2/3 9 3/10- 4 3/5

1) 8 1/5 - 3 2/7 = 41/5 - 23/7 = 41*7/5*7 - 23*5/7*5 = 287/35 - 115/35 = 172/35 =
= 4 32/35

2) 5 6/13 - 2 2/3 = 71/13 - 8/3 = 71*3/13*3 - 8*13/3*13 = 213/39 - 104/39 =
= 109/39 = 2 31/39

3) 9 3/10 - 4 3/5 = 93/10 - 23/5 = 93/10 - 23*2/5*2 = 93/10 - 46/10 = 47/10 = 4 7/10