Multiple choice geometry question please help

Ineed to learn how to solve this problem

The holiday party will cost $160 if 8 people attend.if there are 40 people who attend the party, how much will the holiday party cost

Sample response: if the graph passes the horizontaline test, then the function is one to one. functions that are one to one have inverses that a therefore, the inverse is a hinction compare your response to the sample response above. what did you include in your explanation? a reference to the horizontal-line test d a statement that the function is one-to-one the conclusion that the inverse is a function done