Вариант 2: -20 1/4
Пошаговое объяснение:
(-15 3/4 + (-2 5/6)) + (-1 2/3) = -15 + (-2) +((-3/4 + (-5/6)) + (-1 2/3) = -17 + ((-9-10)/12) + (-1 2/3) = -17 + (-19/12) + (-1 2/3) = -17 + (-1 7/12) + (-1 2/3) = -18 7/12 + (-1 2/3) = -18 + (-1) + (-7/12 + (-2/3)) = -19 + ((-7 +(-8))/12) = -19 + (-15/12) = -19 + (-1 3/12) = -20 3/12 = -20 1/4
