Дроби к наименоьшему общему знаменателю 3/10 и 2/5; 5/9 и 7/18; 1/5 и 7/25; 1/2 и 1/3; 2/11 и 1/3; 5/7 и 1/6.

3/10 и 2/5 = 3/10 и 4/10
5/9 и 7/18 = 10/18 и 7/18
1/5 и 7/25 = 5/25 и 7/25
1/2 и 1/3 = 3/6 и 2/6
2/11 и 1/3 = 6/33 и 11/33
5/7 и 1/6 = 30/42 и 7/42