а) 12 5/12 + 4 1/8 - 4 2/3 = 12 10/24 + 4 3/24 - 4 16/24 = (12 + 4 - 4) + (10/24 + 3/24 - 16/24) =12 - 3/24 = 11 21/24 = 11 7/8
б) 5 9/10 + (5 - 2 8/15) = 5 9/10 + 2 7/15 = (5 + 2) + (27/30 + 14/30) = 7 + 41/30 = 8 11/30
в) 8 8/9 + 2 11/12 - 3 1/4 = (8 + 2 - 3) + (32/36 + 33/36 - 9/36) = 7 + 56/36 = 8 20/36 = 8 5/9
г) 10 - (5 7/8 + 3 5/12) = 10 - (5 21/24+ 3 10/24) = 10 - 8 31/24 = 10 - 9 7/24 = 1 - 7/24 = 17/24