Question 602091
10	x		-	y	=	12.50	.............1	
								
3	x	+		y	=	7	.............2	
Eliminate	y							
					
	
Add the two equations								
13	x				=	20		
/	13							
x	=	20/13						
plug value of			x	in (1)				
10	x		-	y	=	13		
200/13			-	y	=	13		
			-	y	=	13		-200/13
			-	y	=	-31/13		
				y	=	31/13

It has a unique solution	(20/13, 31/13)