Ответ:

3 1/2

Пошаговое объяснение:

1) 2 1/7 * 1 1/20 = 15/7 * 21/20 = 3/1 * 3/4 = 9/4 = 2 1/4

2) 3/8 + 2 1/4 = 3/8 + 2 2/8 = 2 5/8

2) 2 5/8 * 1 1/3 = 21/8 * 4/3 = 7/2 * 1/1 = 7/2 = 3 1/2