Admission is based on a lot of issues. It is hard to know what causes any particular rejection.
@Muad_dib: “I’m guessing the essay was your downfall.”
@Ohm888: “Don’t take this the wrong way but your English is wobbly.”
However, I think that these two comments may have noticed one possible issue. @beatyou1314, your English is way better than my second language, but is still not as good as it should be to get into a very top university such as UCLA (or UC Berkeley). You probably need to take some ESL classes and work on your writing skills. I do understand that Computer Science is not the same thing at Journalism, but it is still valuable to be able to write clearly in whatever language your classes (and subsequently career) will be in.
@beatyou1314: “Igetc: only took 4 of them.”
I didn’t understand what this sentence is trying to say. Does this mean that you got 4 C’s? If so then you don’t have a 4.0. If not, then I can’t even guess what this says.
Regarding EC’s:
“and did 20 hours volunteering, including 10 hours math tutoring.”
20 hours of volunteering is not actually a large amount of volunteering, nor a complete list of ECs. My daughter was required to do many times more than this just to graduate from high school. ECs might have been another issue.
I honestly don’t know whether an appeal will allow you to get more detail regarding why your application was rejected. If so, then filing an appeal might give you useful information that will allow you to know what to do differently next time, and what to work on.