Roberto Trucks Inc. purchased a delivery van on January 1, 2019. Assume this was the company's only capital asset. The following information is available. Cost Estimated useful life Salvage value $11,000 4 years or 75,000 kms. $2,000 The truck was driven 20,000 km in 2019, 40,000 km in 2020, and 15,000 in 2021. Required: 1. Calculate the depreciation for 2019, 2020, and 2021 under each of the following methods: a. Straight-line b. Units-of-production c. Double-declining balance 2. Compare the depreciation expense and net book value for 2019 under each of these methods. 3. If one of management's objectives is to maximize 2019 net income, what method should be adopted