Expert: Lynn Houston - 6/22/2009

Question
Jane covered a distance of 340 miles between city A and city B, taking a total of 5 hours. If part of the distance was covered at 60 miles per hour and the balance at 80 miles per hour, how many hours did she travel at 60 miles per hour?

Answer
distance = time * speed
Let y = distance traveled at 80mph and x=distance traveled at 60mph

340 = 60x + 80y
x+y = 5  (solve for x or y)

x = 5-y (plug in value of x in the first eq)

340 = 60(5-y) + 80y
340 = 300 -60y + 80y
40 = 20y
y = 2, therefore x = 3