North Coast Petroleum holds huge reserves of oil assets. Assume that at the end of 2016, North

Question:

North Coast Petroleum holds huge reserves of oil assets. Assume that at the end of 2016, North Coast Petroleums cost of oil reserves totaled $60,000,000,000, representing 5,000,000,000 barrels of oil.
Requirements
1. Which method does North Coast Petroleum use to compute depletion?
2. Suppose North Coast Petroleum removed and sold 900,000,000 barrels of oil during 2017. Journalize depletion expense for 2017.