# A Delta 727 traveled 2520 miles with the wind in 4.5 hours and 2160 miles against the wind in the same amount of time. How do you find the speed of the plane in still air and the speed of the wind?

Sep 26, 2015

$40 M p h$

#### Explanation:

Let the speed of plane in still air be x mph and speed of wind be y mph

## WITH THE WIND

$S p e e d = x + y = \frac{2520}{4.5} = 560 \ldots \ldots . . \left(A\right)$

## AGAINST THE WIND

$S p e e d = x - y = \frac{2160}{4.5} = 480 \ldots \ldots . . \left(B\right)$

$\left(A\right) + \left(B\right)$

$2 x = 1040$

$x = 520 m p h$

$y = 40 m p h$ ANSWER

CHECK

$\frac{2520}{560} = 4.5 h o u r s$

$\frac{2160}{480} = 4.5 h o u r s$