11.3 How do we adjust for depreciation when we calculate incremental after-tax free cash flow from EBITDA? What is the intuition for the adjustment? Problem 11.13 Explain the concept of equivalent annual cost and how it is used to compare projects with different lives. Problem 11.14 Explain how we decide the optimal time to replace an existing asset with a new one Problem 11.7 What are variable costs and fixed costs? What are some examples of each? How are these costs estimated in forecasting operating expenses