A plane can fly at 385mph in still air. If it can fly 220 miles downwind in the same amount of time it can fly upwind at 165 miles, what is the velocity of the wind?

55 mph

Explanation:

Distance = speed * time, so time = distance / speed.

If x is the speed of the wind, then:

220 / (385 + x) = 165 / (385 - x)

Cross multiply:

220 (385 - x) = 165 (385 + x)

Distribute:

84,700 - 220 x = 63,525 + 165 x

Combine like terms:

21,175 = 385 x

Solve for x:

x = 55

The speed of the wind is 55 mph.