# An airplane flew 3.5 hours with a 40 mph head wind. The return trip with a tail wind of the same speed took 2.5 hours. How do you find the speed of the plane in still air?

##### 1 Answer

Mar 15, 2017

#### Explanation:

Let the velocity of the plane relative to still air be

Let the ground distance be

Distance = velocity

Up wind the velocity

Down wind the velocity