an airplane travels 400 miles against the wind in 5 hours an

an airplane travels 400 miles against the wind in 5 hours and makes the return trip with the same wind in 2 hours. find the rate of the wind.

Solution

This is an RTD problem, Here is the table based on given information.
wind . . . . . . .rate . . . . . . . .time . . . . . . . .distance
against . . . . . r - c . . . . . . . .5 . . . . . . .. . .. 400
with . . . . . . . .r + c . . . . . . . 2 . . . . . . .. . . . 400
--
r-c = 80
r+c = 200
adding down we get
2r = 280
r = 140.