2*1/7· (1*2/3+2*7/9*3,9)

2 1/7 * (1 2/3 + 2 7/9 * 3,9) = 26,77568.

Переведем в десятичные дроби:

2 1/7 = (2 * 7 + 1) / 7 = 15/7 = 2,14.

1 2/3 = (1 * 3 + 2) / 3 = 5/3 = 1,67.

2 7/9 = (2 * 9 + 7) / 9 = 25/9 = 2,78.

1. 2,78 * 3,9 = 10,842.

2. 1,67 + 10,842 = 12,512.

3. 2,14 * 12,512 = 26,77568.