Rate of wind or current problems using 2 variables

Rate of Wind Problem #1

http://www.youtube.com/watch?v=cf0oUu04sCM

Rate of Wind Problem #2: A plane flying against the wind flew 270 miles in 3 hours.  Flying with the wind, the plane traveled 260 miles in 2 hours.  Find the rate of the plane in calm air and the rate of the plane.  

http://www.youtube.com/watch?v=P1aghAIDjGc

Rate of Current Problem #2

http://www.youtube.com/watch?v=cy3qjHiNOfs

Rate of Current Problem #3 

http://www.youtube.com/watch?v=03F0mhQruso