math
posted by zack .
In a storm, a plane flew against the wind and took 9 hours to cover 3,600 miles. The return trip, traveling with the wind, took 1 hour less. find the air speed of the plane, and the speed of the wind.

Speed of plane  x mph
speed of wind  y mph
9(xy) = 3600
xy = 400
8(x+y) = 3600
x+y = 450
add them:
2x = 850
x = 425 , and y = 25