Pls help for correct answer and explain.

Robert and Kerri worked for employers and freelanced on the side. Because they ran into an underpayment penalty last year, they wanted to be sure they paid enough in the current year so they made estimated payments. Below is information on their W2s and estimated payments. What is the amount of tax they will enter on Form 540, Line 72 ? $4,500 $5,092 $8,092 $8,292