Can someone help me to find the slope?

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?

Which of the following equations is equivalent to x/3-6/x=1

Matt had 5 library books. he checked out 1 additional book every week without retuening any books. whats the matching equation