2. An airline wishes to determine how many small (70 seat) and large (120 seat) planes to buy. Each 70-seat plane costs 50 million dollars and each 120-seat plane costs 80 million dollars. They want the total seat capacity of all planes to be at least 300. The small planes have a fuel-efficiency (FE) rating of 5.4; the larger planes have an FE rating of 7.8. They want the weighted average plane FE rating to be no more than 6. (a) (8 marks) Defining variables X1 and X2, formulate this integer model