Решие пример с дробями по действиям: (3 1/5*1 1/24+3*5/6) * 4/21-1 1/9

(3 1/5 * 1 1/24 + 3 * 5/6) * 4/21 - 1 1/9 = 0;

1) 3 1/5 * 1 1/24 = (3 * 5 + 1) / 5 * (1 * 24 + 1) / 24 = 16/5 * 25/24 = (2 * 8 * 5 * 5) / (5 * 3 * 8) = (2 * 5) / 3 = 10/3 = 3 1/3;

2) 3 * 5/6 = (3 * 5) / (3 * 2) = 5/2 = 2 1/2;

3) 3 1/3 + 2 1/2 = 3 + 2 + 1/3 + 1/2 = 5 + (1 * 2) / (3 * 2) + (1 * 3) / (2 * 3) = 5 + 2/6 + 3/6 = 5 + (2 + 3) / 6 = 5 + 5/6 = 5 5/6;

4) 5 5/6 * 4/21 = (5 * 6 + 5) / 6 * 4/21 = 35/6 * 4/21 = (7 * 5 * 2 * 2) / (2 * 3 * 7 * 3) = (5 * 2) / (3 * 3) = 10/9 = 1 1/9;

5) 1 1/9 - 1 1/9 = 1 - 1 + 1/9 - 1/9 = 0.