3. Найдите значение выражения: 1) -36 + 69 + (-17) + (-42) + 32; 2) -8 - (-12) - (-7) + 12 - 20; 3) $$2\frac{3}{4} - (-1\frac{1}{2}) + (-3\frac{5}{6})$$.

Решение: 1) -36 + 69 + (-17) + (-42) + 32 = -36 + 69 - 17 - 42 + 32 = 33 - 17 - 42 + 32 = 16 - 42 + 32 = -26 + 32 = 6 2) -8 - (-12) - (-7) + 12 - 20 = -8 + 12 + 7 + 12 - 20 = 4 + 7 + 12 - 20 = 11 + 12 - 20 = 23 - 20 = 3 3) $$2\frac{3}{4} - (-1\frac{1}{2}) + (-3\frac{5}{6}) = \frac{11}{4} + \frac{3}{2} - \frac{23}{6} = \frac{33}{12} + \frac{18}{12} - \frac{46}{12} = \frac{51}{12} - \frac{46}{12} = \frac{5}{12}$$