First flight = f
second flight = s
Equations
f + s = 365 Equation 1
f = 4s + 5 Equation 2
Solve by substitution
(4s + 5) + s = 365
4s + 5 + s = 365
5s = 365 - 5
5s = 360
s = 360 / 5
s = 72
Find f
f = 4(72) + 5
f = 288 + 5
f = 293
Result
In the flight from Baltimore to Orlando there were 72 people.