Consider the question. The girl scouts earned $30 total from selling delicious cookies. They want to go to the pool. It will cost them $2.50 per person to go and 10 people are going. What is the amount left?
 What is the step-by-step reasoning process to arrive at the answer: 5?
The girls paid $2.50 / person * 10 people = $25. The girls have $30 - $25 = $5 left.