Not as good as they hoped

Sara watched them intently, secretly hoping they would be able to easily get half of them right, leaving her naked and at their mercy. Mary and Susie were furiously trying to get their minds to solve equations and problems that they barely understood how to even do that. Soon, both girls finished and gave Sara their papers. Mary and Susie grinned, expecting things to go in their favor, and embarrass this nerd who thought she knew better.

"Okay, let's see..." Sara smirked as she looked at their answers.

"So, you getting naked?" Mary joked.

"Hang on. Looks like you two had 6 matching answers." Sara began.

Mary and Susie bumped fists in triumph, but before they said anything, Sara continued.

"However, only two of your answers are correct." She said.

"What!?" Both girls said in unison.

"Now hear me out, I can help you. I see where you went wrong. We can still spend a productive hour together. I promise you won't be bored." Sara explained.

"Kinda hard to be boring when you're half naked!" Susie joked.

"Yep! Just because we didn't beat your test doesn't men you can weasel out of our arrangement. 2 correct answers means we get to take two items from you. And to make things interesting, we aren't gonna be taking anything off your feet." Mary explained.

"Well, what did you have in mind?" Sara asked.

Sara at the moment was facing the window looking out into the library. All three sat at opposite sides of a table, their bodies visible from the waist up.

Mary thought a moment before saying, "Let's go with...