How do u solve the question in the picture

In two or more complete sentences, determine the appropriate model for the given data and explain how you made your decision. (1,-1), (2,0.5), (5,1.5), (8,2)

How many $20 bills do you need to have to make $280

Ijust need to see how to do this. so you don’t have to answer all of them just a step by step explanation of one.