Question 433975
Runner I	6	mph					
Runner II	7	mph					
							
Difference in time=	90 minutes				
Train Awill have covered 9	miles	before 	Runner II starts
							
catch up distance=		9	miles				
catch up speed =		7-6	mph			
catch up speed =		1	mph				
							
Catchup time = catchup distance/catch up speed							
catch up time=		9/1			
catch up time=		9 hours