Question

10x-35+3ax=5ax-7a solve for "a" for which the equation is an identity.

Answer 1

$10x-35+3ax=5ax-7a \\ 3ax-5ax+7a = -10x+35 \\ -2ax+7a = -10x+35 \\ a(-2x+7)=-10x+35 \\\\ a= \frac{-10x+35}{-2x+7} \\\\ a = \frac{5(-2x+7)}{(-2x+7)} \\\\ a=5$