i hate math

today i was in math  and im good at it but not if i have to it for the class right?? so my teacher asked me to do a calculation on the white board. my heart dropped and i said :'yeah sure', i walked up to the white board and did my calculations with full convidence. I taught that i did everything good and that the answer was right, it wasnt and she told me when i was standing infront of the class. i began to cry