Answer
$-y-3$
Work Step by Step
Simplifying Rational Expressions
1. Factor the numerator and the denominator completely.
2. Divide both the numerator and the denominator by any common factors.
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Numerator $:$ search for two factors of $-12$ whose sum is $-1$
... these are $-4$ and $3$
$y^{2}-y-12=(y-4)(y+3)$
Denominator = $-(y-4)$
Expression = $\displaystyle \frac{(y-4)(y+3)}{-(y-4)}$
... divide both with the common factor: $(y-4)$
Expression = $\displaystyle \frac{y+3}{-1}$ = $-(y+3)$ = $-y-3$
