logarithms
ln a - ln b= ln a/b
ln 1= 0
ln a +ln b= ln ab
ln e= 1
ln a= ln b is a=b
At what point do you get stuck? Are you able to combine the left-hand side into a single logarithm? After that you can equate the expressions inside the logs (or, equivalently, make both sides exponential to the base so that the logarithm operations get canceled out).