189 Найдите корень уравнения: a) $4(z-6) - 3(z-3) = -8$; б) $-6(6-x) - 5x = -18$; n) $\frac{4}{5}(1.5c-4.5) - \frac{9}{2}(2.1c-6.3)$; r) $\frac{1}{9}(0,96 - 1.8) - \frac{2}{9}(0.26 -0.4)$; B) $\frac{1}{5}(5x-10) - \frac{2}{9}(9x-27) = -9$; г) $4,2(3z - 5) - 1,4(5z - 3) = -5.6$.

Разберем каждое уравнение по порядку: a) $4(z-6) - 3(z-3) = -8$ $4z - 24 - 3z + 9 = -8$ $z - 15 = -8$ $z = -8 + 15$ $\mathbf{z = 7}$ б) $-6(6-x) - 5x = -18$ $-36 + 6x - 5x = -18$ $x - 36 = -18$ $x = -18 + 36$ $\mathbf{x = 18}$ в) $\frac{1}{5}(5x-10) - \frac{2}{9}(9x-27) = -9$ $x - 2 - 2(x - 3) = -9$ $x - 2 - 2x + 6 = -9$ $-x + 4 = -9$ $-x = -13$ $\mathbf{x = 13}$ г) $4,2(3z - 5) - 1,4(5z - 3) = -5.6$ $12,6z - 21 - 7z + 4,2 = -5.6$ $5,6z - 16,8 = -5.6$ $5,6z = 11,2$ $\mathbf{z = 2}$ n) $\frac{4}{5}(1.5c-4.5) - \frac{9}{2}(2.1c-6.3)$; $\frac{4}{5}*1.5c-\frac{4}{5}*4.5 - \frac{9}{2}*2.1c + \frac{9}{2}*6.3=0$ $1.2c-3.6 -9.45c+28.35=0$ $-8.25c+24.75=0$ $-8.25c=-24.75$ $c=3$ r) $\frac{1}{9}(0,96 - 1.8) - \frac{2}{9}(0.26 -0.4)$; $\frac{0.96}{9}-\frac{1.8}{9}-\frac{0.52}{9}+\frac{0.8}{9}= \frac{-0.56}{9}$ $\mathbf{-\frac{0.56}{9}}$