An airline predicts the following pilor requirements for the next 5 quarters: 80, 90, 110, 120, 110. Current staff consistss of 90 pilots. The question of major concern is the nubmer of pilots to hire in each of the next 5 quarters. A pilot must spend the quarter in which she/he is hired in training. The airline's training facilities limit the number of pilots in training to at most 15.