Santiago Co. provides excellent service and high-quality injection molding solutions in Chile. It relies on molding process technologies to meet the precision and performance requirements, since a qualified custom molder includes one injection-molding machine with their two fitting dies. Due to differences in cycle times, cavity (part) configuration, the die A can produce 100 units of 120 litre wheelie bins in 6 hours, while the die B can produce the same quantity of 160 litre wheelie bins in 5 hours. Although Santiago operates on ordering scheme, it operates at most 60 hours of production per week. After producing, wheelie bins are stored in a 15,000 cubic feet stockroom, in which a unit of 120 litre wheelie bin requires 10 cubic feet of space and a 160 litre wheelie requires 20 cubic feet. The contribution of the 120 and 160 litre wheelie bins are $5 and $4.5 per unit. However, the weekly demand of 120 litre wheelie bin is not more than 800 units based on historical data observed. How many units of each type should be produced each week to maximize the total contribution?