How is OPEC beneficial to its member countries?

The purpose of OPEC is to "coordinate and unify the petroleum policies of its Member Countries and ensure the stabilization of oil markets in order to secure an efficient, economic and regular supply of petroleum to consumers, a steady income to producers and a fair return on capital for those investing in the petroleum industry."

Since wxyz is 4, halfof that would be 2.

Answer barren with few trees, in the northern hemisphere;