A scuba diver uses negative number to represent her depths below sea level. she was at a depth of -1.5 meters .then she dove down to a depth of -4.2 meters. what is the difference between those depths ?

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?