Question

Store A has a promotion. If you buy three shirts, you get 25% off the total price of the three shirts. Store B has the same shirts on sale with the promotion that if you buy three shirts, you get the third shirt at a 50% discount. Store C has the same shirts on sale with a 10% discount. Assuming the three stores have the shirts priced equally before any promotion or sale and assuming you want to buy three shirts, which store�s promotion or sale gives you the better deal?

Answer 1

Store A has the best deal.
Lets say shirts are $11 a piece. If you buy 3 that is $33. If you take 25% off, you save $8.25. B only saves $5.50 and C only saves $3.30

Answer 2

So we are assuming that the three shirts have equal price. Let the price of one shirt be a.

In store A:

the cost is (a+a+a) -(25/100)a=3a-0.25a=2.75a

In store B: 

the cost is : a+a+50/100 a =a+a+0.5a=2.5a


In store C:

the cost is
[a-(10/100)a]+[a-(10/100)a]+[a-(10/100)a]=[a-0.1a]+[a-0.1a]+[a-0.1a]
=0.9a+0.9a+0.9a= 2.7a


thus the cost of buying the shirts from stores A, B and C is: 

2.75a, 2.5 a and 2.7 a respectively.

the best deal, is buying from store B, where the cost is the lowest: 2.5a.

Answer: store B