Пошаговое объяснение:
а)
(7 1/2 + 3 2/3) * 6 = (15/2 + 11/3) * 6 = (45/6 + 22/6) * 6 =
= 67/6 * 6 = 67,
б)
(6 + 1 1/3 * 2) * 30 = (6 + 4/3 * 2) * 30 = (18/3 + 8/3) * 30 =
= 26/3 * 30 = 26 * 10 = 260,
в)
5 3/4 * 3 5/7 + 3 5/7 * 1 1/4 = 3 5/7 * (5 3/4 + 1 1/4) = 3 5/7 * 7 =
= 26/7 * 7 = 26