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.
