I really messed up in a subject. How much will it hurt me?

<p>I'm not that good in math, but I decided to take AP Calculus this year to challenge myself, instead of taking the honors course (which is significantly easier).
Unfortunately, my grades have been bad. In the first quarter, my calc average was an 81 and this quarter, we only have one test and despite my best efforts, I got a 75. If I do really well on my midterm I can get my second quarter average back up to the low 80s again, but I was wondering- how much will this hurt me in the admissions process? I applied to a lot of elite schools (including some Ivies, Northwestern, NYU, BC etc... I have safeties too), and I was wondering if getting a C in just one class could be a big factor. :/
...What do you think?</p>

<p>By the way, I have A’s in all of my other classes. My overall average is okay, a low 90s but it’s this class that is bringing me down.</p>

<p>It’s expected by elite schools that you take a rigorous curriculum–including AP calc.<br>
Do everything you can to get a “B” in that class. You don’t want to get a “C.”</p>

<p>I know a girl that was very verbally oriented (got an 800 on the critical reading section) and I’m sure she didn’t get an “A” in calculus (she told me she was having trouble.) I assume she got a “B”, but she got into UPenn anyway. </p>

<p>This is the last time you’ll ever have to do math. Do your best.</p>