#### Answer

$\frac{y-1}{y+9}$

#### Work Step by Step

To simplify, divide both the numerator and denominator by their greatest common factor.
Use factorization to find the GCF.
$\frac{y^2-3y+2}{y^2+7y-18}=\frac{(y-2)(y-1)}{(y-2)(y+9)}=\frac{(y-2)(y-1)\div(y-2)}{(y-2)(y+9)\div(y-2)}=\frac{y-1}{y+9}$