How Do You Solve Logarithmic Expressions Involving Fractions?

[elmers_]

If $$log_2 (5)$$ = x and $$log_2 (3)$$ = y , determine an expression for $$log_2 (15/2)$$, in terms of x and y.
A. xy
B. x + y
C. xy - 1
D. x + y - 1

I'm suppose to solve this by hand but it doesn't seem possible. I tried so many ways but the does not come out as D. which is the answer Can someone explain the steps to this problem? Thanks!

 

[Mark44]

Hint: log₂(15/2) = log₂(15) - log₂(2)