On January 1, 2022, Happy Company purchased equipment for $65,000. The equipment had an estimated life of 10 years, an estimated residual value of $5,000, and was expected to be used to produce 150,000 units over its life. During 2022, the equipment was used to produce 9,000 units and during 2023 it was used to produce 17,000 units. Assume the company uses the units of production depreciation method to depreciate its equipment. Calculate the book value of the equipment at December 31, 2023.