Marlon is hungry and finds himself at a restaurant that only sells pizza by the slice. Help Marlon decide how many slices he should purchase. Each slice of pizza costs $3.

Assuming that Marlon has at least $15 to spend, how many slices should he buy? Why?

What will his net benefit (total benefit - total costs) be after that purchase?
What will happen to his net benefit
if he buys 1 more slice?