7th Grade Math Helps: Discounts

To determine the percentage of a discount, use the formula:

amount of discount                         N
__________________ = ______________
Original cost                                          100

If a store sells a supply for a regular price of $47.50 and it is discounted to a price of $39.25, what is the percent of the discount?
1) Find the amount of discount:
47.50-39.25= 8.25

2) Fill in the equation:

8.25 =          n
____ _______
47.50          100

3) Cross multiply to get:
47.50N= 825

4) Divide both of the numbers above by the original cost, in this case, 47.50.
47.50n / 47.50 = N
825/47.50= 17.4

5) N= 17.4% so the amount of the discount is 17.4%

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