Step-by-step explanation:
Speed = Distance/Time
If one commuter plane averaged 200 mph flying to a city
Time taken to fly to the city will be;
t1 = d/200
d = 200t1
If he used 120 mph returning to the international airport, the total time used to the airport will be
t2 = d/120
d = 120t2
Since the distance are the same;
200t1 = 120t2
t1/t2 = 120/200
t1/t2 = 3/5
5t1 = 3t2
t1 = 3t2/5
Substitute into t1+t2 = 4
3t2/5 +t2 = 4
8t2/5 = 4
8t2 = 20
t2 = 20/8
t2 = 2.5min
Since d = 120t2
d = 120(2.5)
d = 300miles
Hence the total distance between the two airports is 300miles
