You can also derive the formula for the difference in time. Where d is the distance and w is the speed of the wind and r is the windspeed of the plane. Then the additional time it takes is
(2dw^2)/(r3-rw^2)
…I think.

To calibrate airspeed instruments, the procedure to overcome any wind is to fly in two opposite directions for some specified distance at the same indicated airspeed, then with a little math you can get the actual airspeed and you will know how far off your instruments are. Too much information?

You have the additional (and easier to think of) case of the wind being a 90 degree crosswind for both directions. To compensate for the crosswind, you have to fly with a crab angle, and your effective distance traveled through the air is higher to cover the same ground distance (increasing time of flight both directions).

I guess a good example is a plane making a 100km trip at 100km/h. If the wind is against it from A to B at 50km/h, the plane’s net speed is 50km/h so the one-way trip takes 2 hours. Then on the way back if the plane’s net speed is 150km/h, the 100km return trip will take 0.67 hours resulting in a total trip time of 2.67 hours. Compare this to if there was no wind and the plane flew 100km each way at 100km/h; the trip would take 2 hours.