A machine costing $180,000 was purchased may 1. The machine should be obsolete after four years and, therefore, no longer useful to the company. The estimated salvage value is $15,000. Calculate the depreciation expense for each year of its expected useful life using each of the following depreciation methods: (a) straight-line, (b) double-declining balance. For double-declining balance, do not round until your final answer. Round your final answers to the nearest dollar.