Math CentralQuandaries & Queries


Question from Matthew:

Retail $99
Mark-up is 80%

What is the equation to find the original (wholesale) price (55)?


Hi Matthew,

Think about what you would do if you knew the original price and you wanted to calculate the retail price after an 80% markup. Suppose the original price was $\$p.$ To calculate the retail price you would find 80% of $\$p$ and add it to $\$p.$ Thus the retail price would be

\[\$p + 0.80 \times \$p = 1.80 \times \$p.\]

Thus you have

\[1.80 \times \$p = \$99.\]

Since $\$99$ is 1.80 times $\$p$ you know that $\$p$ is $\$99$ divided by 1.80.

I hope this helps,

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