G3.3 It is given that $\log \frac{x}{2}=0.5$ and $\log \frac{y}{5}=0.1$. If $\log x y=c$, find $c$.
$\begin{array}{l}\log \frac{x}{2}+\log \frac{y}{5}=0.5+0.1 \\ \log x y-1=0.6 \\ \Rightarrow c=\log x y=1.6\end{array}$