Well, if the truck traveled for one hour, that means the car traveled for two. 60+70+70=200 It's not that difficult to just guess and check, even if it's a bit time consuming. Let's try three hours for the truck. 60+60+60+70+70+70+70=460 That's too much, so we'll try two hours. 60+60+70+70+70=330 The truck traveled two hours, and the car traveled three hours, since the car traveled one hour longer than the truck. All together, the car and truck drove a total of 5 hours.