а) 3/4 + 5/12 = 9/12 + 5/12 = 14/12 = 7/6 = 1 целая 1/6
б) 3 1/2 : 1 1/6 = 7/2 : 7/6 = 7/2 * 6/7 = 6/2 = 3
в) 1 - 4/9 * 3/8 = 1 - 1/6 = 5/6
