Question 863966
-1	x	+	1	y	=	-1	.............1				
1	y	=	-1	+	1	x					
/	1	=									
	y	=	-1	+	1	x					
-2	x	+	1	y	=	7		.....................2			
Substitute y in		(2)									
-2	x	+	1	(	-1	+	1	x	)	=	7
-2	x	+	-1	+	1	x	=	7			
-2	x		1	x	=	8					
-1	x	=	8								
/	-1										
x=	-8      										
Plug the value of x in (1)											
-1	x	+	1	y	=	-1					
-1	*	-8      	+	1	y	=	-1				
8      	+	1	y	=	-1						
1	y	=	-9      								
/	1										
y=	-9      										
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