Answer
$13$
Work Step by Step
Using the laws of exponents, the given expression, $
\dfrac{-91y^{-3}}{-7y^{-3}}
,$ is equivalent to
\begin{array}{l}\require{cancel}
(-91\div(-7))y^{-3-(-3)}
\\\\=
13y^{-3+3}
\\\\=
13y^{0}
\\\\=
13(1)
\\\\=
13
.\end{array}
For more complicated problems, it is helpful to remember that you can flip the location of numbers with negative exponents. In other words, you can move numbers with a negative exponent that are in the numerator to the denominator, and you can move numbers with a negative exponent in the denominator to the numerator.
