<PRE><B>Question 414401</B>
The speed of a plane is 120 miles/hour in a calm.
 With the wind it can cover a certain distance in 4 hours, but against the wind
 it can cover only 3/5 of that distance in the same time.
 Find the velocity of the wind.
:
I think you are making this more complicated than it is:
Let x = velocity of the wind
then
(120+x) = effective speed with the wind
and
(120+x) = effective speed against the wind
:
Change 3/5 to .6
:
Write a distance equation; dist = time * speed
:
&quot;against&quot; dist = .6 times &quot;with&quot; distance
4(120-x) = .6(4(120+x)
480 - 4x = .6(480+ 4x)
480 - 4x = 288 + 2.4x
480 - 288 = 2.4x + 4x
192 = 6.4x
x = {{{192/6.4}}}
x = 30 mph is velocity of the wind 
:
:
Check this by finding the actual distance for each trip
4(120+30) = 600 mi
4(120-30) = 360 mi
Find the fraction that 360/600 = .6 which we would expect if we did this right</PRE>