Well, the opposite of an exponent is a square root. However, in this case, it is to the power of 3. So in order to find p, you must do the cube root on both sides in order to get your answer:
[tex]p^3=3[/tex]
[tex]\sqrt[3]{p^3} =\sqrt[3]{8}[/tex]
[tex]p=2[/tex]
