1. The problem is to solve part (c) of number 6. Since the exact problem statement is not provided, please provide the full problem or the expression for part (c) of number 6. 2. Generally, to solve algebraic problems, we use formulas such as solving equations, factoring, or applying algebraic identities. 3. Please provide the specific equation or expression for part (c) of number 6 so I can assist you step-by-step.