Question

A clothing store charges $30 for 12 pairs of socks. A student says that the unit price is $0.40 per pair. What is the error? What is the correct unit price?

Answer 1

Their error is that they divided 12 by 30, instead of 30 by 12 in order to get the price per pair

the correct unit price is $2.50 per pair

2.5 * 12 = 30

Answer 2

You must divide $30 by 12 to find out how much each pair costs.  The correct unit price is $2.50 per pair.