If you have trouble with math you should defintley go to your math teacher and tell them that you are having trouble and they could "reteach" the math you are having trouble with. You should also take your time at home and review over the assingments you have done. While you are in math class you should take notes so you can study them. If you still don't understand consider finding a private tutor that could help you.
I hope this help you:)