SOLUTION: Jerilyn has a $10 coupon and a 15% discount coupon for her favorite store. The store has a policy that only one coupon may be used per purchase. When is it best for Jerilyn to use

Question 989963: Jerilyn has a $10 coupon and a 15% discount coupon for her favorite store. The store has a policy that only one coupon may be used per purchase. When is it best for Jerilyn to use the $10 coupon, and when is it best for her to use the 15% discount coupon?
I'm not kidding, this is an actual question from my textbook.
Found 2 solutions by addingup, MathTherapy:
Answer by addingup(3677) (Show Source): You can put this solution on YOUR website!
If Jerilyn is buying an item that costs $10 or less, she's better off using the 15% coupon. Why? Let's use an example, let's say she is buying a T-shirt for $8. Let's say she hands in the $10 coupon. She just lost $2, because she paid for a $8 item with a $10 coupon.
Now let's say she's buying an $15 pair of sandals. She hands in the $10 coupon and pays $5. She got the sandals for just $5.
Answer by MathTherapy(10552) (Show Source): You can put this solution on YOUR website!
Jerilyn has a $10 coupon and a 15% discount coupon for her favorite store. The store has a policy that only one coupon may be used per purchase. When is it best for Jerilyn to use the $10 coupon, and when is it best for her to use the 15% discount coupon?
I'm not kidding, this is an actual question from my textbook.

Items for $66.67 will have the same final cost, with either.
Items costing < $66.67 are cheaper with the $10 coupon
Items costing > (more than) $66.67 are cheaper with the 15% discount
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