Dr. Murphy wants to calculate the scrap value of a grill 20 years after purchase. According to him, using the declining-balance method, better represents depreciation. However he does not know what figure to use for depreciation rate. She goes on craigslist, and observes that a grill that was purchased for $245,000 three years ago, has a current salvage value of $180,000. What is a good estimate of the value of her grill after 20 years, if she buys one for $260,000 today?

Please answer using a detailed hand calculation or an excel with formulas used, if compounding interest tables were used please state.