Recently, while working on some math homework, Carmen and Mario got into a little argument. During the dispute, a part of their assignment was destroyed. All that remained of one
particular problem is shown below.

Carmen was furious. “Way to go, Mario! Now there is no way to get this problem correct! We don't
even know what f(x) is.”
“Wait a minute!” Mario quickly responded. “I’m pretty sure we can solve this anyway.”
Carmen shook her head.
Who is correct? Explain completely why and what the other person might be forgetting.