To solve this question, you will need to manipulate the given equation and substitute 2^y with x in order to get back the equation in part b. Since the question uses the keyword hence, it needs part b's answers thus when seeing this kind of question you need to work backwards to solve the given equation.

One more important thing to take note is that you need to sub back x with 2^y as we are solving for y. This also means that the solution 2^y = -3/2 must be rejected as 2^y cannot be negative as exponential functions cannot be negative.