Please Help Thank You

Question 1:

$\log_216$ is equal to 4, because $2^4=16$.

So now, we are trying to find what x satisfies $x^4=81$, so $\boxed{x=3}$.

Question 2:

For the biggest value of b, we need to find 2 values in the ranges of f(x) and g(x) that, when multiplied together, results in the biggest possible result. That would be $-5\cdot-2=\boxed{10}$

Thank you so much for your help. I can comprehend these questions so much better now. Thank You!!!