UCLA vs. CMU

Hi everyone, I have been admitted to UCLA for pre math and CMU in Tepper Business School. I am now struggling between the two choices, can anyone please give me some advice? UCLA has a strong math apartment, but the problem is it is too big to me. I do not like big classes with over 100 students. CMU has a much smaller class, but I am not sure if business is a good choice for undergraduate major. Seems like math would be a better major for undergraduate, and it is also my favorite subject. I am also not sure the opportunity of jobs related to each major of these two schools. Can anyone please give me some advice? Thank you so much!