I'm gonna take a stab in the dark here and guess what you're trying to do... (I'm sick and my brain isn't 100% working)
So you want to rearrange this: and solve for ee(S)??
From the law of logarithms, it can be re-written as:
Then get rid of the logarithm by raising both sides by exp:
Then just expand and solve for ee(S). I think you can carry on from here.