Oilco must determine how many barrels of oil to extract during each of the next two years.

If Oilco extracts x1 million barrels during year 1, each barrel can be sold for $30 - x1.

If Oilco extracts x2 million barrels during year 2, each barrel can be sold for $35 - x2.

The cost of extracting x1 million barrels during year 1 is x2 1 million dollars, and the cost of extracting x2 million barrels during year 2 is 2x2 2 million dollars. A total of 20 million barrels of oil are available, and at most $250 million can be spent on extraction. Formulate an NLP to help Oilco maximize profits (revenues less costs) for the next two years.