1) 0,8(3а-14)-0,6(6а-8) а=3 целых 1/13

Решите задачу:

$0.8(3a-14)-0.6(6a-8) = \\ = 2.4a - 11.2 - 3.6a + 4.8 = \\ = - 1.2a - 6.4 \\ \\ a = 3 \frac{1}{13} \\ \\ - 1.2 \times 3 \frac{1}{13} - 6.4 = - \frac{12}{10} \times \frac{40}{13} - \frac{32}{5} = \\ = - \frac{48}{13} - \frac{32}{5} = - \frac{(48 \times 5 + 32 \times 13)}{65} = \\ = - \frac{240 + 416}{65} = - \frac{656}{65} = - 10 \frac{6}{65}$