Question 993904
The easy way:  They cover 45 miles in 3 hours.  Their combined speed must be 15 miles an hour.  Thus the slower guy travels at 5 mph and the faster at 10 mph.

The harder way:  If we call the rate of the slower rider R, the faster rider travels at 2R.  Since they travel the same 3 hours, one guy travels 3R miles and the other travels 6R miles.  Added together, they cover 45 miles, or

3R + 6R = 45
9R = 45
R = 5
2R = 10 miles per hour