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| Math Central | Quandaries & Queries |
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Question from Dylan, a student: shirts on sale for 25% off, the sale price is 12.75. What is the original price? |
Hi Dylan,
With just a little algebra you can solve this.
Suppose the original price is $P$ dollars and the sale price is $S$ dollars. The discount is 25% so if you knew the original price then you would calculate the sale price using
\[P - 0.25 P = S.\]
Taking out a common factor of $P$ on the left side gives
\[P(1 - 0.25) = 0.75 P = S.\]
But you know $S,$ so solve for $P.$
Penny
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