Chapter 11 - Rational Expressions and Functions - 11-2 Multiplying and Dividing Rational Expressions - Practice and Problem-Solving Exercises - Page 674: 28

$=\frac{(w-3)(w+3)}{4}$

$(w^2-8w+15)\times\frac{w+3}{4w-20}$ $=(w^2-5w-3w+15)\times\frac{w+3}{4(w-5)}$ $=[w(w-5)-3(w-5)]\times\frac{w+3}{4(w-5)}$ $=(w-3)(w-5)\times\frac{w+3}{4(w-5)}$ $=\frac{(w-3)(w+3)(w-5)}{4(w-5)}$ $=\frac{(w-3)(w+3)}{4}$