You buy a used car listed as $ 10,000 at a discount of 10 percent. However, you also pay 10 percent sales tax. Thus you end up writing a check for? $
The answer would also be the same if you applied tax before the discount
10% of 10,000 is 1,000 so you have 11,000
10% of 11,000 is 1,100 so you get 9,900