Question 319981
Dan is preparing for a 10-mile race. 
first 5 miles average speed of 6 miles per hour,
next 3 miles at an average speed of 8 miles per hour,
final 2 miles at an average speed of 10 miles per hour. 
..
first leg time = 5/6 hours
second leg time = 3/8 hours
third leg time = 2/10 hours
..
total time = 5/6+3/8+2/10
LCM = 480
5*80 + 3*60+2*48 / 480
400+180+96 / 480
676/480
= 1.41 hours