9. 15r(s²-16) / 45r²(s-4) =

9. $$ \frac{15r(s^2-16)}{45r^2(s-4)} = \frac{15r(s-4)(s+4)}{45r^2(s-4)} = \frac{s+4}{3r} $$.

Ответ: $$ \frac{s+4}{3r} $$