Leslie, Inc., followed the practice of depreciating its building on a straight-line basis. A building was purchased in 2019 and had an estimated useful life of 25 years and a residual value of $20,000. The company’s depreciation expense for 2019 was $15,000 on the building. What was the original cost of the building?

a. $395,000

b. $500,000

c. $520,000

d. Cannot be determined from the information given.