Question 504368
Kris	x 	mph						
Amy	x+	5	mph					
..								
They are moving towards each other								
								
So add up their speed.								
								
combined speed = x+			x	+	5			
(	2	x	+	5	) 			
Time = 	6	hours						
Distance =   	510	miles						
Distance = speed * time								
(	2	x		+5	)*	6	=	510
12	x 	+	30	=	510			
12	x 	=	510	+	-30			
12	x 	=	480					
/	12							
x=	40	mph	Kris					
Amy	40	+	5	=	45	mph