Question 184163

Distance(d) equals Rate(r) times Time(t) or d=rt;  r=d/t and t=d/r
Let r=speed of the plane in still air
Let s=speed of the wind

If the plane is flying with the wind, we add the wind speed;
Against the wind, we subtract.  So:
r+s=900/3=300------------------------------eq1
r-s=900/4=225------------------------------eq2

add eq1 and eq2:
2r=525
r=262.5 mph---------------------speed of plane in still air
substitute r=262.5 mph into eq1:
262.5+s=300
s=300-262.5=37.5 mph-------------speed of the wind

Hope this helps---ptaylor