Algebra
posted by Delia on .
Beth is a bush pilot in Alaska. On a recent trip, she flew 600 miles with a tail wind in four hours. On the return trip, it took five hours to fly the 600 miles against the wind. Find the speed of the plane with no wind.
Could you please explain how to solve this problem? Thank you so much! :D

let the speed of the plane with no wind be x mph
let the speed of the wind be y mph
4(x+y) = 600 or
x + y = 150 (1)
5(xy = 600 or
x  y = 120 (2)
Add (1) and (2) etc.