Define the variables and set up system of equations which would solve the problem.
Boeing 777s seat 300 passengers and are priced at $160 million, Boeing 747s seat 400 passengers and are priced at $200 million each and European Airbus A321s seat 200 passengers and are priced at given $60 million. You are purchasing manager of the airline company and have the $6,180 million budget to buy novel aircraft to seat the total of 13,200 passengers. The company has the policy of supporting U.S. industries, and you have been instructed to purchase twice as many U.S.- manufactured aircraft as foreign aircraft. Given selection of 3 aircraft, how many of each must you order?