2000 AIME Problem 13

In the middle of a vast prairie, a fire truck is stationed at the intersection of two perpendicular straight highways. The truck travels at 50 miles per hour along the highways and at 14 miles per hour across the prairie. Consider the set of points that can be reached by the fire truck within six minutes. The area of this region is m / n square miles, where m and n are relatively prime positive integers. Find m+n.