Gwen is buying 3 identical pairs of shoes that have a total cost of $40.50 after the discount of 40 percent off. what is the regular price of each pair?

Let's say p is the principal cost of the total (original) we can setup the equation p-.4p=40.5 => .6p=40.5 => p=67.5
So the cost without the sale is $67.50
For the original price of each pair divide this by 3.
67.5/3=22.5
Final
Each pair costs $22.50 without the sale.
Hope I helped :)

According to Wikipedia: "In mathematics, a function is a relation between a set of inputs and a set of permissible outputs with the property that each input is related to exactly one output."

So based of this we need to look for a set where one of the x values or the y values is the same, and the other number is different.

B.
(1,4) and (1,1) both have the same x, but different y!