Question 16
If
$$
\begin{gathered} \dfrac{4^x}{2^{x+y}}=8,\\ \dfrac{9^{x+y}}{3^{5y}}=243, \end{gathered}
$$
$x$ and $y$ are real numbers, then $xy$ equals:
$$
\begin{gathered} \dfrac{4^x}{2^{x+y}}=8,\\ \dfrac{9^{x+y}}{3^{5y}}=243, \end{gathered}
$$
$x$ and $y$ are real numbers, then $xy$ equals: