Вычислите: a) 3/4 + 4/5; б) 2/3 + 1/7; в) 2/13 + 0; д) 5/12 + 3/4; г) 5/9 + 2/11; е) 5/6 + 7/8.

a) 3/4 + 4/5 = 15/20 + 16/20 = 31/20 = 1 целая 11/20. б) 2/3 + 1/7 = 14/21 + 3/21 = 17/21. в) 2/13 + 0 = 2/13. д) 5/12 + 3/4 = 5/12 + 9/12 = 14/12 = 7/6 = 1 целая 1/6. г) 5/9 + 2/11 = 55/99 + 18/99 = 73/99. е) 5/6 + 7/8 = 20/24 + 21/24 = 41/24 = 1 целая 17/24.