Make this chart. Let r = rate in still air, and let w = the rate of the wind. | Rate | Time | Distance ----------------------------------------- With the wind | r+w | 4 | 1680 ----------------------------------------- Against wind | r-w | 5 | 1680 Rate x Time = Distance (r+w)(4) = 1680 (r-w)(5) = 1680Divide the first through by 4 and the second through by 5: Add those two equations term by term, and the w's will cancel and you can find r. Then substitute to find w. Edwin