Question 420261
Children's Tickets		x 				
Adult tickets	------------	y						
x	+	y	=	120	.............1		
7	x	+	9	y	=1000	.............2		
									
multiply (1)by 	-9				
Multiply (2) by	1			
-9	x	+	-9	y	=	-1080			
7x	+	9	y	=	1000												
Add the two equations									
									
-2	x	=	-80			
									
/-2								
									
x=40	Children's Tickets						
									
plug value of x in (1)									
									
x	+	y	=	120			
40+y	=	120			
y	=	120-40	
y	=	80			
y	=	80		Adult tickets