<PRE><B>Question 536960</B>
David  	x 	mph						
Casey	x+	15	mph					
..								
They are moving away from each other								
								
So add up their speed.								
								
combined speed = x+		1	x	+	15			
(	2	x	+	15	) 			
Time = 	3	hours						
Distance =   	261	miles						
Distance = speed * time								
(	2	x		15	)*	3	=	261
6	x 	+	45	=	261			
6	x 	=	261	+	-45			
6	x 	=	216					
/	6							
x=	36	mph	David  					
Casey	36	+	15	=	51	mph		
</PRE>