Answer
$\frac{y}{2}$
Work Step by Step
We can simplify by canceling out common factors of both fractions and then multiplying.
$\frac{27y^3}{21}\times\frac{7}{18y^2}
=\frac{/\!\!3\times/\!\!9\times y\times /\!\!y^2}{/\!\!3\times/\!\!7}\times
\frac{/\!\!7}{2\times/\!\!9\times /\!\!y^2}=\frac{y}{2}$
