Решение 3/4:5/6+2 1/2*2/5-1:3 2/7

3/4 : 5/6 + 2 1/2 * 2/5 - 1 : 3 2/7 = 229/230.

1) 3/4 : 5/6 = 3/4 * 6/5 = 1/2 * 3/5 = 3/10;

2) 2 1/2 * 2/5 = 5/2 * 2/5 = 1/1 * 1/1 = 1/1 = 1;

3) 1 : 3 2/7 = 1 : 23/7 = 1 * 7/23 = 7/23;

4) 3/10 + 1 = 3/10 + 10/10 = 13/10;

5) 13/10 - 7/23 = 299/230 - 70/230 = 229/230.

Ответ: 3/4 : 5/6 + 2 1/2 * 2/5 - 1 : 3 2/7 = 229/230.