(3 1/2-2 5/6)*21/26+4 6/13

(3 1/2 - 2 5/6) * 21/26 + 4 6/13 = 5

1) 3 1/2 - 2 5/6 = 3 3/6 - 2 5/6 = 2 9/6 - 2 5/6 = 4/6 = 2/3

2) 2/3 * 21/26 = (1*7)/(1*13) = 7/13

3) 7/13 + 4 6/13 = 4 13/13 = 5

Ответ: 5.