Chapter 8, Problem 8.14BE

What is the primary purpose of preparing a trial balance? a) To calculate net profit or lossb) To check the mathematical accuracy of the ledger accountsc) To prepare the income statementd) To report cash flows

Machinery was purchased for $78,500 on January 1, 2018. Shipping costs were $2,200 and installation expenses totaled $4,300. It is estimated that the machinery will have a $15,000 salvage value at the end of its 8-year useful life. What is the amount of accumulated depreciation on December 31, 2020, if the straight-line method of depreciation is used?

I am trying to find the accurate solution to this general accounting problem with appropriate explanations.