Ответ:

1) 1/4 + 1/5 = 5/20 + 4/20 = 9/20

2) 3/5 + 3/4 = 12/20 + 15/20 = 27/20

3) 1/2 + 5/8 = 4/8 + 5/8 = 9/8

4) 5/6 + 3/8 = 40/48 + 18/48 = 58/48= 29/24

5) 3/4 + 2/9 = 27/36 + 8/36 = 35/36

6) 3/4 + 4/5 = 15/20 + 16/20 = 31/20

7) 3/4 + 1/4 = 4/4 = 1

8) 6/7 + 3/70 = 60/70 + 3/70 = 63/70 =9/10

9) 6/21 + 7/22 = 132/462 + 147/462 = 279/462= 93/154

10) 5/24 + 7/60 = 25/120 + 14/120 = 39/120= 13/40