Question

{(5ас^2)/(а^2-9с^2)} × {(а-3с)/(ас)}

Answer 1

$\frac{5ac ^{2} }{a ^{2}-9c ^{2} }* \frac{a-3c}{ac}= \frac{5c}{(a-3c)*(a+3c)}*(a-3c)= \frac{5c}{a+3c}$