In this video, we learn how to back out the tax from a receipt. If you have a receipt where you see how much you paid and know the tax rate, except you want to figure out the cost of the item before the tax. First, take the cost of the item including tax and what the tax rate is. To figure out the original price, let x equal the cost of the item. Add the tax to the cost of the item which will equal the cost you paid. Perform the equation 1x+(tax rate)= (total price). After you figure this equation out, you will know what the cost of the item is that you are looking for!