a) 7- 4 5\9 = 6 9\9 -41/9 = 63/9-41-9 = 63-41/9 = 22/9 = 2 4/9
б) 4 3/10 + 1 5/12 = 43/10 + 17/12 = 258 + 85/60 = 343/60 = 5 43/60
в) 6 15/21 + 2 9/14 = 141/21 + 37/14 = 282+111/42=393/42= 9 15/42
г) 5 1/6 - 3 3/4 = 31/6 - 15/4 = 62 - 45 /12 = 17/12 = 1 5/12