It takes a private airplane 8.75 hours to make the 2100-mile flight from

atlanta to los angeles and 5 hours to make the return trip. Assuming that the wind blows at a constant rate from Los Angeles to atlanta, find the airspeed of the plane and the wind rate.

i know that i have to use the d=rt formula....but when i get to the part where i make the formulas: (r+w)=2100 and (r-w)=2100.......i don't know what to do after that