This is an awkward question to me, it was not covered in class.
Suppose:
$\begin{align*} \log_b 2 &= A, \\ \log_b 3 &= B, \\ \log_b 5 &= C. \end{align*} $
Then, use the change-of-base formula to evaluate
$\log_{b^2} 5$
and
$\log_{\sqrt b} 2 .$
As an example answer, we're given $\log_3 b$ becomes $1/B$.
Hopefully someone understands where they're coming from.