привидите к наименьшему общему знаменателю дроби
3/8 и 5/12
2/15 и 3/10
10/17 и 13/34
4/13 и 3/4
1/9 и 1/7
9/14 и 2/21
1/20 и 1/ 30
1) 3/8, 5/12 = 9/24, 10/24
2) 2/15, 3/10 = 4/30, 9/30
3) 10/17, 13/34 = 20/34, 13/34
4) 4/13, 3/4 = 16/52, 39/52
5) 1/9, 1/7 = 6/54, 8/54
6) 9/14, 2/21 = 27/42, 4/42
7) 1/20, 1/30 = 3/60, 2/60