3/10 + 8/25 = НОК 10 и 25 = 50. 15/50 + 16/50 = 31/ 50
13/14 - 2/7 = Нок 14 и 7 = 14. 13/14 - 4/14 = 9/14
4 3/8 + 5 1/4 = Нок 8 и 4 = 8. 4 3/8 + 5 2/8 = 9 5/8
14 5/9 - 3 5/6 = Нок 9 и 6 = 18. 14 10/18 - 3 15/18 =13 28/18 - 3 15/18 = 10 13/18
6 2/3 + 3 5/12 = Нок 3 и 12 = 12. 6 8/12 + 3 5/12 = 9 13/12 = 10 1/12