Luis wants to buy a skateboard for $79.99. All merchandise is discounted 12%. What is the total cost of the skateboard if Luis has to pay a state sales tax of 6.75%?

First you need to figure out the cost of the skateboard after the discount but before the sales tax. By doing 100%-12% you figure out how much of the original cost you are paying 88%. Then you multiply 79.99 (original cost) and 88% (how much you pay) which gets you 70.39. Then you figure out the sales tax by multiplying 70.39 by 6.75% which gives you 4.75 (the sales tax). And the last thing you need to do is add the cost before tax (70.39) and the tax (4.75).

The skateboard costs $75.14