"Use the One-to-One Property to solve the equation for x."

http://img183.imageshack.us/img183/6...90928at426.jpg

According to my book, the 1-1 property states that:

"For a>0, and a≠1, $\displaystyle a^x = a^y$ if and only if x = y."

I don't know how I can translate that into my problem...