#### Explanation:

Overbooks by 5%, therefore $240 \times 1.05 = 252$ passengers booked on the airplane.
We then need to calculate 5% of this, so $252 \times 0.05 = 12.6$.
We then need to round this to $13$ as you cannot have $0.6$ of a person.
$252 - 13 = 239$ passengers to turn up to the flight.

#### Explanation:

Start by noting that the plane has 240 seats, and if the airline overbooked by 5%, meaning that 105% of the seats are booked, then 240*105%=240*1.05=252 seats were sold. Of these $252$ tickets, 5% of them will not be used, meaning that 100%-5%=95% will be used. 252*95%=252*0.95=239.4~=240. Since there are $240$ passengers, no passengers, if everything goes according to average, no payout should be necessary.