From the information given,
probability that a flight arrives on time = 95% = 95/100 = 0.95
Probability that a flight will not arrive on time = 1 - 0.95 = 0.05
Given 480 scheduled flights,
number of flights that will not arrive on time = 0.05 x 480 = 24
The best estimate of the number of these flights that will not arrive on time = 24