4. (Linear/Integer Programming: big-number constraints) A company has two suppliers (A and B) and three warehouses (1, 2, and 3). Unit Shipping Cost 1 2 3 A 4 6 4 B 7 7 8 Supplier A Unit Production Cost 4 B 3 Warehouse 1 2 3 Sale Prices 18 17 15 The company can purchase from either A or B, or both A and B. If the company decides to purchase from supplier A, it needs to pay supplier A an upfront setup fee of $700; otherwise, the company does not need to pay the setup fee to supplier A. Similarly, if the company wants to purchase from supplier B, the upfront setup fee is $200. The maximum production capacity of each supplier is 150 units, and each warehouse requires at least 40 units. The objective is to determine which supplier(s) to use and to determine the shipping plan in order to maximize the profit. Formulate (do not solve) this problem as an LP problem. Hint: Consider using the following decision variables: Y = {0,1} denotes whether to use supplier A (YA = 1 means yes, Y = 0 means no), and YB = {0,1} denotes whether to use supplier B (YB = 1 means yes, YB = 0 means no).