The owner of an audio store received a shipment of portable stereos at a cost of $102.30 each. If he sells the stereos for $181.09 each, what is the percent markup?

So here, we are starting with two numbers: the original price, and the price after the percent increase.

First, we need to find the differences between the prices to figure out how much of a difference the percent made. $181.09 - $102.30 = $78.79

$78.79 is how much money the original price was increased by. We can find the percent change using this, since this number is what percent of the original price went up.

So now: $78.78 / $102.30 =.77018

And now, we convert that to percent: 77%

The markup was 77%.