camping story

Boat B starts 100 miles East of Boat A. Boat B travels North at a rate of 75 mph. Boat A travels South at a rate of 50 mph for 3 hours. A) What is tha rate of change between the distance of the two boats after two hours? After 3 hours Boat A changes direction and heads West at a rate of 70 mph. B) How fast are the boats moving away from each other after a total of 6 hours?