maths
posted by thommini .
Two cyclists start biking from a trail's start 3 hours apart. The second cyclist travels at 10 miles per hour and starts 3 hours after the first cyclist who is traveling at 6 miles per hour. How much time will pass before the second cyclist catches up with the first from the time
the second cyclist started biking?
( This question is very hard, please help me, please help with the working. thanks )

When the second cyclist starts, they are 18 miles apart. (3 hours times the speed of the first biker).
After that, the distance between the bikers shrinks at a rate of 10  6 = 4 miles/hr.
The distance between bikers becomes zero after 18/4 = 4.5 hours. That is when the latestarting biker [passes the other. 
OR
let the time taken from when the second rider leaves till they meet be t hours
10t = 6t + 18 , (their distances are the same)
4t = 18
t = 4.5 
thanks a lot !!