Acme estimates it costs $$1\mathrm{.}50$ per month for each unit of this appliance carried in inventory at the end of each month. Currently, Acme has $120$ units in inventory on hand for this product. To maintain a level workforce, the company wants to produce at least $400$ units per month. They also want to maintain a safety stock of at least $50$ units per month. Acme wants to determine how many of each appliance to manufacture during each of the next $4$ months to meet the expected demand at the lowest possible total cost.