Пошаговое объяснение:

12/35 * 21/15 = 4/5 * 3/5 = 12/25

72/33 * 11/30 = 12/3 * 1/5 = 12/15 = 4/5

25/51 * 17/8 * 44/75 = 25/3 * 1/8 * 44/75 =

25/24 * 44/75 = 1/6 * 11/3 = 11/18