Given his plot of land, a farmer uses labor (10 workers), capital (5 pieces of equipment), and fertilizer (5 tons) to produce corn. He has figured that each additional worker hired over the course of the growing season adds 5000 bushels to his crop. Each additional unit of capital, on the other hand, adds 10000 bushels to his annual yield. Finally, adding one unit of fertilizer increases the size of his crop by 8000. The annual wage of labor is $10,000, the yearly cost of one unit of capital is $4000, and a ton of fertilizer is also 4000. Is the farmer's mix of inputs optimal? If you were to advise the farmer to change the mix of its inputs, what would your advice be?