Ответ:

18 8/21

Пошаговое объяснение:

1) 6 2/7 - 3 5/7 = 2 4/7

2) 4 1/6 * 2 4/7 = 25/6 * 18/7 = 75/7 = 10 5/7

3) 7 2/3 + 10 5/7 = 7 14/21 + 10 15/21 = 17 29/21 = 18 8/21