I feel like I'm an idiot/not smart academically. Help!?

Since I've started liking this guy who does pretty well in school, I've noticed how average I am. I'm a freshman in high school and I can't easily solve simple math equations such as 180-58=x without thinking for a while. I don't think it's because I'm not academically up to it since my PSAT scores were pretty good, but it's just that I don't really know how to motivate myself to do good in school, I guess. I also don't have practice. I go to a private prep school where people take AP's for freshman year and do well in it too. I don't want to be average or BELOW average, because what good is it to go to a private prep school if you're not going to be one of the above average students? We pay 15,000 dollars a year for me to go to this school, so it's important that I take advantage of going there! What should I do? -sigh-