Hi everyone. I'm taking my very first physics course and can't seem to get a grasp on it. I can solve some problems without problems but get stuck at simple things. I need a little hint on this problem: A car drives from A to B, half the time at 55 km/h and the other half at 90 km/h. On the way back, the car travels half the distance at 55km/h and the other half at 90km/h. What is the average speed from B to A? Thanks in advance!