YOU SAID:

Im bad at math so a teacher assistant comes and helps me

INTO JAPANESE

私は数学が苦手なので、アシスタントの先生が来て手伝ってくれます

BACK INTO ENGLISH

I'm not good at math, so an assistant teacher will come and help me.

INTO JAPANESE

私は数学が苦手なので、補助の先生が来て手伝ってくれます。

BACK INTO ENGLISH

I'm not good at math, so an assistant teacher will come and help me.