9. A farmer has 1000 acres of land avallable for planting corn and wheat. It costs $30 to plant an acre of corn and $20 to plant an acre of wheat. He has a total budget of $22,000 and he wants to spend all of it, and he wants to use all of his acres of land. Let x denote the number of acres of corn and y the number of acres of wheat planted. Set up (do not solve) a system of equations that be could use to determine how many acres of each crop be should plant