a) 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 = 3 6/7
г) 4 8/15 - 2 13/15 = 1 20/15 = 2 5/15 = 2 1/3