Answer: 3/8q^3 + 9
Step-by-step explanation:
1. combine like terms 5/8q^3 - 1/4q^3, need to make denominator the same to subtract so multiply 2/2 by 1/4q^3, 5/8q^3 - 2/8q^3 = 3/8q^3
2. final answer is : 3/8q^3 + 9