Answer
$\frac{-3}{x-2}$
Work Step by Step
To simplify, divide both the numerator and denominator by their greatest common factor.
Use the distributive property to find the GCF.
$\frac{-21}{7x-14}=\frac{-21}{7(x-2)}=\frac{-21\div7}{7(x-2)\div7}=\frac{-3}{x-2}$