Combine any like terms on each side of the equation: x-terms with x-terms and constants with constants. Arrange the terms in the same order, usually x-term before constants. If all of the terms in the two expressions are identical, then the two expressions are equivalent. That is how you find which expression is equivalent.
The reason why the answer would be p^16/q^12 would be because, that if it is exponents. You always. Always. Subtract or Add depending if its multiplication or subtraction. So p^24-p^8 would be p^16. q^4-q^12 would be q^12.
Therefore, your answer would be <em><u>p^16/q^12</u></em>
