(3 1/14 - 2 5/21) · 2 7/15 - 2 13/18 = -2/3
1) 3 1/14 - 2 5/21 = 3 3/42 - 2 10/42 = 2 45/42 - 2 10/42 = 35/42 = 5/6
2) 5/6 · 2 7/15 = 5/6 · 37/15 = (1·37)/(6·3) = 37/18 = 2 1/18
3) 2 1/18 - 2 13/18 = -(2 13/18 - 2 1/18) = -12/18 = -2/3
ответ: (-2/3).
