Bizarro arithmetic

The presence of operators with spaces like '+ ' was leading to display bugs with the preview of students' answers. Removing them seems to have caused no harm and makes the display bug go away.
I've finally had the chance to look into this, and you want to leave the division operators there, but remove the addition and subtraction with spaces.  That is because the Numeric context only has spaced versions of multiplication and division, not addition and subtraction.  So you are creating new operators that don't have full definitions, here.  In particular, they don't contain the strings needed for their output, and so they produce nothing.  But since they are tied to your classes they do operate properly other than that.

If you remove the division operators as you do here, then division with spaces will not be checked by the bizzaro mathematics.