If the denominators are not the same, then you have to use equivalent fractions which do have a common denominator . To do this, you need to find the least common multiple (LCM) of the two denominators. To add fractions with unlike denominators, rename the fractions with a common denominator. Then add and simplify.
You will pay $71.4 for a item with original price of $89.25 when discounted 20%. In this example, if you buy an item at $89.25 with 20% discount, you will pay 89.25 - 17.85 = 71.4 dollars.