A car drove 50 m/h for 3 hours, 65 mh for 30 minutes and 70 my for 1 hour. What was the cars average speed?

Speed is distance divided by time. First you have to find the total distance, so you would do (50*3) + (65*.5) + 70 (1). After you get that answer, you divide it by the time which would be 3 hours+.5 hours+1 hours. Just remember s=d/t.