Question 534045
The 1st rider will be back at the start every
10 minutes, that is 10 min, 20 min, 30 min, etc.
The 2nd rider arrives at start 2 minutes later
each times around. The 5th time around, rider
#2 is behind 10 minutes. 
#2 has gone 5 times around in  12*5 = 60  min
In 60 min, rider #1 has gone 6 times around,
and they meet at start
The answer is 60 min or 1 hr