1. Let's first clarify the problem you are working on in Q4 to understand step 5 better. 2. Please provide the exact problem statement or the steps leading up to step 5. 3. Step 5 usually involves a key operation like simplification, substitution, or applying a formula. 4. Once you share the details of step 5, I will explain it in a clear, step-by-step manner with all intermediate work. 5. This will help you understand the logic and calculations behind that step. Please provide the problem or step 5 details so I can assist you effectively.