Introduction: Some Simple Math Problems

Intuitively, we might respond that since the same distance is being covered each way, that we can just halve the difference in the speeds of the two trips to get an average speed for the round trip of 75km/h. Makes sense, right? WRONG! We must actually calculate the time involved and the distance. (500km at 100km/h = 5 hours) + (500km at 50km/h = ................
................