FRAC: Fraction arithmetic

syntax: FRAC({Add|Subtract|Multiply|Divide|+|-|*|/}, frac 1, frac 2, frac 3 ...)

The first argument to the function is the name of the arithmetic operation to be performed which can be either the literal word name as in Add, Subtract, Multiply or Divide or the arithmetic symbol for the operation such as +,-,*,/. The operation specified will be performed on all following fractions entered into this function
Add fractions frac 1 + ... + frac n and returns the result as a fraction or Subtract fractions frac 1 - ... - frac n and returns the result as a fraction or Multiply fractions frac 1 * ... * frac n and returns the result as a fraction or Divide fractions frac 1 / ... / frac n and returns the result as a fraction