# Can someone help me with this log question?

1. Jan 21, 2009

### 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!

2. Jan 22, 2009

### Staff: Mentor

Hint: log2(15/2) = log2(15) - log2(2)