Chapter 7 - Rational Functions - 7.3 Multiplying and Dividing Rational Expressions - 7.3 Exercises - Page 580: 20

$= \frac{(m-8)}{(m-3)}$

$\frac{m^{2}+6m+9}{m^{2}+5m+6} \times \frac{m^{2}-6m-16}{m^{2}-9}$ $= \frac{(m+3)(m+3)}{(m+3)(m+2)} \times \frac{(m-8)(m+2)}{(m+3)(m-3)}$ $= \frac{(m+3)(m+3)(m-8)(m+2)}{(m+3)(m+2)(m+3)(m-3)}$ $= \frac{(m+3)(m-8)(m+2)}{(m+2)(m+3)(m-3)}$ $= \frac{(m-8)(m+2)}{(m+2)(m-3)}$ $= \frac{(m-8)}{(m-3)}$