Shum way Oil uses successful-efforts accounting and also provides full-cost results as well. Under full-cost, Shum way

Question:

Shum way Oil uses successful-efforts accounting and also provides full-cost results as well. Under full-cost, Shum way Oil would have reported retained earnings of $42 million and net income of $4 million. Under successful-efforts, retained earnings were $29 million, and net income was $3 million. Explain the difference between full-costing and successful-efforts accounting.