Пошаговое объяснение:

№1

1) 8/27 * 9/7 = 8/3 * 1/7 = 8/21

2) 8/21 : 4/7 = 8/21 * 7/4 = 2/3 * 1/1 = 2/3

№2

1) 2 2/3 : 24/35 = 8/3 * 35/24 = 1/3 * 35/3 = 35/9

2) 35/9 : 2 7/9 = 35/9 : 25/9 = 35/9 * 9/25 = 7/1 * 1/5 = 7/5 = 1 2/5