Aplane flies 1800 miles in 9 hours, with a tailwind all the way. the return trip on the same route, now with a headwind, takes 12 hours. assuming both remain constant, find the speed of the plane and the speed of the wind. [hint: if x is the plane's speed and y the wind speed (in mph), then the plane travels to its destination at xplusy mph because the plane and the wind go in the same direction; on the return trip, the plane travels at xminusy mph.]