5.281 Вычислите:

а) 4 1/7 + 12 5/7 = 16 6/7

б) 9 8/15 + 6 13/15 = 15 + 21/15 = 16 6/15 = 16 2/5

в) 5 4/7 - 1 5/7 = 4 11/7 - 1 5/7 = 3 6/7

г) 4 8/15 - 2 13/15 = 3 23/15 - 2 13/15 = 1 10/15 = 1 2/3