Do i need to measure what's on the paper or measure a real object

Math each whole number with a rational,exponential expression

Acar started driving from city a to city b, distance between which is 620 miles, at a rate of 60 mph. two hours later a truck left city b and started moving towards city a at a rate of 40 mph. how many hours after the truck's departure will the two meet?

Can someone me with this? i’m not sure what to put for my equations.