Question 807986
let x be the distance traveled
y the speed

x/y = t the right time

Increased speed
x/(y+2) = t-4

decreased speed
x/(y-2)=t+6

x/y =t

x=yt
substitute x in (1)
yt/(y+2) = t-4

yt=(y+2)(t-4)

yt=yt-4y+2t-8
2t-4y=8..........................(1)

--
x/(y-2)=t+6

yt/(y-2)=t+6

yt=(y-2)(t+6)
yt=yt+6y-2t-12

2t-6y=-12...............................(2)

2    	t		-4    	y	=	8    	.............1	
Total value								
2    	t		-6    	y	=	-12    	.............2	
Eliminate	y							
multiply (1)by		-3    						
Multiply (2) by		2    						
-6    	t		12    	y	=	-24    		
4    	t		-12    	y	=	-24    		
Add the two equations								
-2    	t				=	-48    		
/	-2    							
t	=	24    						
plug value of			t	in (1)				
2    	t		-4    	y	=	8    		
48    			-4    	y	=	8    		
			-4    	y	=	8    		-48    
			-4    	y	=	-40    		
				y	=	10    		

x=yt
x=24*10
=240 miles