Before they can say, «I can't do algebra,» they already have. (edutopia.org)
It is like a mathematics teacher in high school who might say to a student, «Verily, verily I say unto thee, except thou canst do decimals and fractions, thou canst in no wise do algebra.» (religion-online.org)
It is not that the teacher will not allow you to do algebra because you are a bad person; you just won't be able to do basic algebra if you are not in command of decimals and fractions. (religion-online.org)