Recall your d = rt, distance = rate * time
so... hmm if the plane has a still air speed of say "r", when it's going with the wind, is not really going "r" fast, is going "r + 40 ", because the wind is adding 40mph to its speed, is really moving.
and when the plane is going against the wind, is not really going "r" fast either, is going " r - 40 ", because the wind is eroding speed from it.
now, it went 2240 miles for say "t" hours, and it did 1920 miles for the same length of time, "t" hours.
and surely you know how much that is.
so... hmm if the plane has a still air speed of say "r", when it's going with the wind, is not really going "r" fast, is going "r + 40 ", because the wind is adding 40mph to its speed, is really moving.
and when the plane is going against the wind, is not really going "r" fast either, is going " r - 40 ", because the wind is eroding speed from it.
now, it went 2240 miles for say "t" hours, and it did 1920 miles for the same length of time, "t" hours.
and surely you know how much that is.