Micheal earns $3.90 per hour as a server at a restaurant. in addition, he earns an average of 18% tips on his food sales. is the amount of money that he earns proportional to the number of hours that he works.

He earns 18% tips on his food sales. So, his tips are proportional to the amount of food he sells.

From what you know about the restaurant business, what would have to be true for his tips to be proportional to the amount of hours he works?

Do you think that situation (Michael's amount of food sales being the same every hour) is likely in a real restaurant?