An airplane can travel 440 mph in still air. If it travels 950 miles with the wind in the same length of time it travels 810 miles against the wind, what is the speed of the wind?
Let speed of wind be W
Total speed when travelling with the wind: 440 + W
Time it takes to travel WITH the wind:
Time it takes to travel AGAINST the wind:
------ Cross-multiplying
950(440) – 950W = 810(440) + 810W
– 950W – 810W = 810(440) – 950(440)
– 1,760W = - 140(440)
– 1,760W = - 61,600
W, or speed of wind = , or mph