Simplify the following expression: 4 / y to the - 3 power.

The mathematical expression of the given above is 4/y^-3 where only the denominator is raised to exponent - 3. Remember that the expression x^-n may also be expressed as 1/x^n. Thus, for the given, transfer the y^-3 of the denominator to the numerator to give the final answer of 4y³.