Apackage express carrier is considering expanding the fleet of their aircraft used to transport packages. there is a total of $350 million allocated for purchases. two types of aircraft may be purchased - the c1a and c1b. the c1a costs $25 million and the c1b costs $18 million. the c1a can carry 6 pounds of packages, while c1b can only carry 4 pounds of packages. the company needs at least 10 new aircraft. it takes 150 hours per month to maintain c1a and 110 hours to maintain the c1b. there are a total of 1200 hours of maintenance time available per month. formulate as an integer programming problem to maximize the number of pounds that may be carried.