A promotion

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?

Correct answer:

x = A

Step-by-step explanation:

$$\begin{gathered} s_1=a+a+a-0.25\cdot 3a=3\cdot 0.75\cdot a=2.25a \\ {s}_2=a+a+a-0.5\cdot a=2.5a \\ {s}_3=a+a+a-0.1a-0.1a-0.1a=2.7a \\ {s}_1<s_2<s_3 \\ x=A \end{gathered}$$

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