Well, lets check how much is the value of dvd plus tax that she must paid.
Sales tax is 7% of 18$ = 0.07 . 18 = 1.26$
Therefore, she must pay..
18$ + 1.26$ = 19.26$ (Why adding? not subtracting? because the tax is some extra cash that you must pay to the store, along with the product also)
In conclusion, we can confirm that Torri has enough money to buy that precious birthday present for her parents. Because she has 20$, and just have to pay 19.26$ for the dvd.
