1. Найдите значение выражений.

а) 3 4/4 + 2 4/7 = 3 + 1 + 2 + 4/7 = 6 + 4/7 = 6 4/7 б) 2 4/9 - 1 5/6 = (2 + 4/9) - (1 + 5/6) = 1 + 4/9 - 5/6 = 1 + (8/18 - 15/18) = 1 + (-7/18) = 1 - 7/18 = 11/18 в) 7 11/15 + (3 1/30 - 1 9/20) = 7 11/15 + (3 + 1/30 - 1 - 9/20) = 7 11/15 + 2 + (2/60 - 27/60) = 7 11/15 + 2 - 25/60 = 7 11/15 + 2 - 5/12 = 9 - 5/12 = 8 7/12.