Question 200086
A search plane has a cruising speed of 250 mph and carries enough fuel for at
 most 5 hrs of flying. 
If there is a wind that averages 30 mph and the direction of search is with the
 wind one way and against it the other, how far can the plane travel before it
 has to turn back?
:
Let d = one way distance
:
250+30 = 280; speed with the wind
250=30 = 220; speed against the wind
:
Write a time equation: Time = dist/speed
:
out time + return time = 5 hrs
{{{d/280}}} + {{{d/220}}} = 5
Multiply equation by 3080 (LCD) to let rid of the denominators
11d + 14d = 5(3080)
25d = 15400
d = {{{15400/25}}}
d = 616 miles then it has to turn back
:
:
Check solution in original equation, find the times
{{{616/280}}} + {{{616/220}}} =
2.2 + 2.8 = 5 hrs