Решение по действиям:
1) 4 - 7/12 = 3 5/12
2) 3 5/12 + 1 5/6 = 4 + (5/12 +5/6) = 4+ (5/12+10/12) = 4+15/12 = 5 3/12 =
= 5 1/4
3) 5 1/4 + 2 1/3 = 21/4 + 7/3 = 63/12 +28/12 = 91/12 = 7 7/12
4) 7 7/12 - 1 1/4 = 91/12 - 5/4 = 91/12 - 15/12 = 76/12 = 6 4/12 = 6 1/3