Porter Business Products acquired equipment on January 1, 2015 for $320,000. The equipment has an estimated useful life of 5 years and an estimated residual value of $20,000. The equipment is expected to produce 200,000 units. During 2015, the equipment produced 24,000 units and during 2016, produced 60,000 units. Calculate the depreciation expense for 2015 and 2016 for the following methods:

Straight line
Double declining balance
Units of production