Question 870020
correct answer-----------x
wrong answer-------------y

x+y=15

8x-4y=72

1.00	x	+	1.00	y	=	15.00	.............1	
Total value								
8.00	x		-4.00	y	=	72.00	.............2	
Eliminate	y							
multiply (1)by		4.00						
Multiply (2) by		1.00						
4.00	x		4.00	y	=	60.00		
8.00	x		-4.00	y	=	72.00		
Add the two equations								
12.00	x				=	132.00		
/	12.00							
x	=	11.00						
plug value of			x	in (1)				
1.00	x	+	1.00	y	=	15.00		
11.00		+		y	=	15.00		
				y	=	15.00		-11.00
				y	=	4.00		
				y	=	4.00		
11 correct answers