After eating four slices of pizza, you are offered a fifth slice for free. You turn down the fifth slice. Your refusal indicates that the

marginal benefit is positive for the fourth slice and negative for the fifth slice.

Explanation:

In the case when four pizza slices are eaten and you have offered for the fifth one for free so here you refuse as the marginal utility of the fifth unit is negative so the consumption with respect to the fifth units would reduced the total utility also the marginal benefit for the fourth slice is positive but it is inverse for the fifth one

what are your options to your question?

borrow money from the government then pay the government back 5k