Question : Two cars on the German Autobahn, a highway with no speed limit, start from the same point and travel north at constant speeds of 170 km/h and 220 km/h respectively. After four hours, how far apart (in kilometers) would the two cars be?
In this question, if I calculate the relative speed = 170 + 220 = 390 km/h and time as 4 hours, then calculate the distance as 97.5 km, why is that wrong?