An airplane flies against the wind from A to B in 8 hours. The same airplane returns from B to A, in the same direction as the wind, in 7 hours. Find the ratio of the speed of the airplane (in still air) to the speed of the wind. Select the correct option:
A) 5	B) 10	C) 15	D) 20	E) 25
Let x = speed of airplane in still air, y = speed of wind and D the distance between A and B. Find the ratio x / y   Against the wind: D = 8(x - y), with the wind: D = 7(x + y)   8x - 8y = 7x + 7y, hence x / y = 15   correct answer 15
<result>C</result>
An airplane flies against the wind from A to B in 8 hours. The same airplane returns from B to A, in the same direction as the wind, in 7 hours. Find the ratio of the speed of the airplane (in still air) to the speed of the wind.