On June 1, Michael Company purchased equipment at a cost of $120,000 that has a depreciable cost of $90,000 and an estimated useful life of 3 years or 30,000 hours.

Using straight-line depreciation, calculate depreciation expense for the first year.

a. $17,500

b. $12,500

c. $30,000

d. $40,000

The answer is A but i need help understanding how this was done. thank you