Can someone tell me the formula of how to calculate depreciation?

Ohio, Inc., which uses a process-cost accounting system, began operations on January 1 of the current year. The company incurs conversion cost evenly throughout manufacturing. If Ohio started work on 3,000 units during the period and these units were 70% of the way through manufacturing, it would be correct to say that the company has:

A. 3,000 physical units in production.