A commuter plane provides transportation from an international airport to surrounding cities. One commuter plane averaged 200 mph flying to a city and 120 mph returning to the international airport. The total flying time was 4 h. Find the distance between the two airports.

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

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