1 1/5-3 1/5*(2 1/2-1 3/7):2 1/7

Решим пример по действиям, начиная с действий в скобках:

1) 2 1/2 - 1 3/7 = (2 * 2 + 1)/2 - (1 * 7 + 3)/7 = 5/2 - 10/7 = 5 * 7/14 - 10 * 2/14 = 35/14 - 20/14 = (35 - 20)/14 = 15/14;

2) 3 1/5 * 15/14 = (3 * 5 + 1)/5 * 15/14 = 16/5 * 15/14 = (16 * 15)/(5 * 14) = 24/7;

3) 24/7 : 2 1/7 = 24/7 : (2 * 7 + 1)/7 = 24/7 : 15/7 = 24/7 * 7/15 = (24 * 7)/(7 * 15) = 24/15 = 8/5;

4) 1 1/5 - 8/5 = (1 * 5 + 1)/5 - 8/5 = 6/5 - 8/5 = (6 - 8)/5 = -2/5 = -4/10 = -0,4.

Ответ: -0,4.