(6-9 3/5)*(-1 2/3)-12:(-3/4+1/8)

(6 - 9 3/5) * (-1 2/3) - 12 : (-3/4 + 1/8) = 25 1/5.

1) 6 - 9 3/5 = 6 - 48/5 = (6 * 5 - 48 * 1)/5 = (30 - 48)/5 = -18/5 = - 3 3/5;

2) -3/4 + 1/8 = 1/8 - 3/4 = (1 * 1 - 3 * 2)/8 = (1 - 6)/8 = -5/8;

3) -3 3/5 * (-1 2/3) = - 18/5 * (-5/3) = 6;

4) 12 : (-5/8) = 12 * (-8/5) = -96/5 = -19 1/5;

5) 6 - (-19 1/5) = 6 + 19 1/5 = 25 1/5.

Ответ: 25 1/5.