Упростите выражение: a) 8 + 7k - 3k + k - 11k; б) 4(c – 1) – 7(c - 5) - 2(3c + 8); в) \frac{4}{13}(6,5n - 3\frac{1}{4}m) - 3,2(\frac{5}{8}n - 0,5m).

Решение: a) 8 + 7k - 3k + k - 11k = 8 + (7 - 3 + 1 - 11)k = 8 + (8 - 14)k = **8 - 6k** б) 4(c - 1) - 7(c - 5) - 2(3c + 8) = 4c - 4 - 7c + 35 - 6c - 16 = (4 - 7 - 6)c + (-4 + 35 - 16) = -9c + (31 - 16) = **-9c + 15** в) \frac{4}{13}(6,5n - 3\frac{1}{4}m) - 3,2(\frac{5}{8}n - 0,5m) = \frac{4}{13}(\frac{13}{2}n - \frac{13}{4}m) - \frac{32}{10}(\frac{5}{8}n - \frac{1}{2}m) = \frac{4}{13} \cdot \frac{13}{2}n - \frac{4}{13} \cdot \frac{13}{4}m - \frac{32}{10} \cdot \frac{5}{8}n + \frac{32}{10} \cdot \frac{1}{2}m = 2n - m - 2n + \frac{16}{10}m = -m + \frac{8}{5}m = -\frac{5}{5}m + \frac{8}{5}m = **\frac{3}{5}m**