1. Let's clarify step 4 by reviewing previous steps to understand the context. 2. If you provide the exact problem or steps 1 to 3, I can explain step 4 clearly. 3. Generally, step 4 involves applying a rule or formula derived earlier. 4. For example, if step 4 is simplifying an expression, break it down into smaller parts. 5. If it's solving an equation, isolate the variable using inverse operations. 6. Please share the problem or previous steps to give a detailed, learner-friendly explanation specifically for your step 4.