Al Rayyan company purchased a new assembly equipment on the 1st of January 2015, which costed $ 150,000 with a residual value of $ 24,000 and estimated useful life of 5 years or 210,000 units. The equipment produced 51,000 units in 2015 and 45,000 units in 2016. The company's fiscal year ends on 31 December of each year. Under the double-declining balance method, what will be the depreciation expense on 31 December 2016?

a. 25,200

b. 30,000

c. 36,000

d. 60,000