When driving the 9 hour trip home, Sharon drove 450 miles on the interstate and 165 miles on country roads. Her speed on the interstate was 20 more than on country roads. What was her speed, in miles per hour, on country roads?

Among the most famous of all meteor showers are the perseids, which occur each year in early august. in some areas the frequency of visible perseids can be as high as 40 per hour. given that such sightings are poisson events, calculate the probability that an observer who has just seen a meteor will have to wait at least five minutes before seeing another.