Выполните действия с дробями

1/2 + 1/3 = 3/6 + 2/6 = 5/6 
1/4 + 2/5 = 5/20 + 8/20 = 13/20
2/3 + 1/4 = 8/12 + 3/12 = 11/12
3/4 + 2/5 = 15/20 + 8/20 = 23/20 = 1 3/20 = 1,15
5/7 - 1/6 = 30/42 - 7/42 = 23/42
3/4 - 1/3 = 9/12 - 4/12 = 5/12
1/8 + 1/4 = 1/8 + 2/8 = 3/8
2/3 - 5/9 = 6/9 - 5/9 = 1/9
1/2 - 5/12 = 6/12 - 6/12 = 1/12
5/12 - 2/9 = 15/36 - 8/36 = 7/36
1/8 + 7/12 = 3/24 + 14/24 = 17/24
3/4 - 1/6 = 9/12 - 2/12 = 7/12
5/9 + 3/4 = 20/36 + 27/36 = 47/36 = 1 11/36
23/40 - 3/8 = 23/40 - 15/40 = 8/40 = 1/5
9/35 - 3/28 = 36/140 - 15/140 = 21/140 = 3/20