posted by s .
an airplane flew with the wind for 30 minutes and returned the same distance in 45 minutes. If the cruising speed of the airplane was 320 mph what was the speed of the wind ?
speed with wind = 320+x
speed against wind = 320-x
distance with wind = .5(320+x)
distance against = .75(320-x)
but those distances were the same, so ...
.5(320+x) = .75(320-x)
multiply each side by 4 to clear the decimals and solve