Question: How can I simplify the way I write simplification problems?

I'm creating a randomly generated question bank that generates the following STYLE or problem:

12x^-4y²
3x⁶y^-5

I'm currently trying to use the answer type "formula without simplification," as I'd like to avoid the students putting the questions in as the answer, and this has been driving me crazy for hours now.

I have tried the "maple" function to simplify. E.g.:

$ANS = maple("( $C1*( $V1^$A1 )*( $V2^$B1 ) ) / ( $C2*( $V1^$A2 )*( $V2^$B2 ) )");

But it always throws an error.

I have simply done the math in the algorithm section, so you end up with an answer variable like this:

$ANS = -4.0*(((z)^2.0)/(5.0*((p)^9.0)))

However, it will still count all answers submitted as incorrect.

Any help would be GREATLY appreciated =/.

Variable name clarification
I have $C1 and $C2, which are the constants of the numerator and denominator, respectively ("12" and "3" in the example).
I have $V1 and $V2 which are the first and second variable, respectively, (in the example, "x" and "y").
I have $A1 and $A2, which are the exponents for the variable $V1 in the numerator and denominator, respectively.
I have $B1 and $B2, which are the exponents for the variable $V2 in the numerator and denominator, respectively.

All these generate from some interesting conditions to create the problems I want (no variables named i, e, or o, for example,) but all properly initialize.