Construct the objective function and the system of inequalities for the given situation. Remember to define the variables first. Do not solve the system. Johnson Lumber can convert logs into either lumber or plywood. In a given week, the mill can turn out 400 units of production, of which 100 units of lumber and 150 units of plywood are required by regular customers. The profit on a unit of lumber is $20 and on a unit of plywood  is $30.