Question 398684
A commuter plane provides transportation from an international airport to surrounding cities.
 One commuter plane averaged 280 mph flying to a city and 120 mph returning to the international airport.
 The total flying time was 3 h. Find the distance between the two airports.
:
Let d = distance between airports
:
Write a time equation, time = dist/speed
:
{{{d/280}}} + {{{d/120}}} = 3 
Multiply by LCM of 280 and 120, 840:
840*{{{d/280}}} + 840*{{{d/120}}} = 3(340)
Clear the denominators, and you have
3d + 7d = 2520
10d = 2520
d = 252 mi between airports
;
:
Check this, find the time for each trip:
252/280  + 252/120 =
.9 + 2.1 = 3 hrs