Question

21(4-6у)=у-42 розвязать

Answer 1

$21(4 - 6y) = y - 42 \\ 84 - 126y = y - 42 \\ 84 - 126y - y = - 42 \\ - 126y - y = - 42 - 84 \\ - 127y = - 42 - 84 \\ - 127y = - 126 \\ y = \frac{126}{127}$