YOU SAID:

Dont you know how to do math

INTO JAPANESE

数学のやり方がわからない

BACK INTO ENGLISH

I don't know how to do math

INTO JAPANESE

やり方を知らない

BACK INTO ENGLISH

I don't know how to do this.

INTO JAPANESE

やり方を知らない

BACK INTO ENGLISH

I don't know how to do this.