Explanation:
Let the speed of jet be j and speed of wind be w.
Flying against the wind a jet travels 1710 miles in 3 hours
   Distance = 1710 miles
   Time = 3 hours
   We have
      Distance =  Speed x Time
       1710 = Speed x 3
       j - w = 570 miles per hour ----------------eqn 1
Flying with the wind the same jet travels 6230 miles in 7 hours
   Distance = 6230 miles
   Time = 7 hours
   We have
      Distance =  Speed x Time
       6230 = Speed x 7
       j + w = 890 miles per hour ----------------eqn 2
eqn 1 + eqn 2
      2 j = 1460
       j = 730 mph
Substituting in eqn 2
     730 + w = 890
        w = 160 mph
Speed of jet is 730 miles per hour and speed of wind is 160 miles per hour.
