Question 1031838
Set w = the wind speed.
The time t1 for the 250 km leg is the distance 250 / the speed (300 - w)
The time t2 for the 680 km leg is the distance 680 / the speed (300 + w)
t1 + t2 = 4 hours
{{{250/(300-w)+680/(300+w)=4}}}
w = 205.86 is the wind speed.
Solving completely by hand is fairly tedious.
I used www.wolframalpha.com with the above equation.
If your instructor needs a more detailed solution,
let me know.