Answer
$\frac{x-2}{x+1},x\ne-1, x\ne-10$
Work Step by Step
$\frac{x^2+8x-20}{x^2+11x+10}$ (factor both numerator and denominator, Also $x\ne-1, x\ne-10$ to keep the denominator non-zero)
=$\frac{(x-2)(x+10)}{(x+1)(x+10)}$ (Dividing both numerator and denominator by x+10)
=$\frac{x-2}{x+1},x\ne-1, x\ne-10$
