1. б) Вычислите: -2 + (11/24 + 5/6) : 1 15/16 - 2/5

-2 + (11/24 + 20/24) : (31/16 - 2/5) = -2 + (31/24) : (155/80 - 16/80) = -2 + (31/24) : (139/80) = -2 + (31/24) · (80/139) = -2 + (31/3) · (10/139) = -2 + 310/417 = -834/417 + 310/417 = -524/417