Two different airlines have a flight form San Francisco to New York that departs each week day morning at a certain time. There is a 70% chance that the first airline’s flight is fully booked on a particular day, and there is a 60% chance that the second airline’s flight is fully booked on that same day. Moreover, when the first airline’s flight is full, there is a 77% chance that the second one is also full.

a) What is the probability that a seat is available for you on one weekday if you have to fly from San Francisco to New York using one of these airlines?

b) What Is the probability that the first airline’s flight is fully booked if you find out that the second one is fully booked?