Against the wind a small plane flew 210 miles in 1 hour and 10 minutes. The return trip took only 50 minutes. How do you determine the speed of the plane?
Speed of the plane
We are told
Adding  and 
Against the wind you have:
where I used the fact that velocity=distance/time and changed time in minutes.
When the wind is in the same direction you get:
From the first equation:
and using this into: