Lebos and Slavia require both corn and barley. Their respective lands, however, have different capabilities in terms of growing these foods. Suppose Lebos can produce at a maximum of either 4 units of corn or 4 units of barley on every acre of land. Slavia can produce at a maximum of either 3 units of corn or 9 units of barley on every acre of land.

1. Assuming a linear technology for producing either corn or barley, how many units of corn must be given up to have one unit of barley in Lebos (i.e. what is Lebos's opportunity cost of producing barley)? Please include a detailed explanation of how you got your answer.