Old purchase price: $
Find percentage increase: $
Add the percent increase to the purchase price:
An increase of 325% means 425% total ($12750)
As it's stated an increase is the plus to the original condition. Therefore in this case is 100% (original price) + 325% (the increase).
You can see it form the following formula
Then if we solve for
Or as I say in the answer
Now you just need to add the tax, just joking...
Hope this helps