When modeling hourly pay which part of the equation is used to represent the total pay?

When it comes to hourly pay, you are trying to find the amount made over so many hours. Since the hourly amount is constant, multiply the hourly pay by the amount of hours.

In some cases, there is also an extra amount of money, which you add this amount to (say, you earn ten dollars for walking your neighbor's dog, and then get an additional 5 per hour you watch the dog.)

So, you model this by:

Amount Per Hour x hours + additional pay = total amount of money