Verified answer

Ответ:

1/4

Пошаговое объяснение:

9/15 : (3 - 5/7 : 1 4/21) = 1/4

1. 5/7 : 1 4/21 = 5/7 : 25/21 = 5/7 * 21/25 = 3/5

2. 3 - 3/5 = 2 2/5

3. 9/15 : 2 2/5 = 9/15 : 12/5 = 9/15 * 5/12 = 1/4