A furniture shop stocks two types of chairs, model A and model B. Model A costs RM 100 per unit while model B costs RM 300 per unit. The shop receives a shipment once a month of not more than 50 chairs of which there must be at least 10 chairs of each model. From past experience, the shop can reasonably expect to sell at most 35 chairs of model A and at most 25 chairs of model B. The profit for model A and model B are RM 30 and RM 70 each respectively. By using the graphical method, how many chairs of each model should be included in each shipment to maximize profit? What is the maximum profit?