Question 419685
$15 tickets ----- x numbers
$0.25 tickets------y numbers
...
x+y = 500
15x+0.25y = 105

With dollar !5 ticket the system cannot be solved. you geta negative value
But if you take $0.15 as the value then it is possible to work out.

1	x	+	1	y	=	500	.............1	
0.15	x	+	0.25	y	=	105	.............2	
								
multiply (1)by 					1			
Multiply (2) by					-4			
1	x	+	1	y	=	500		
-0.6	x	+	-1	y	=	-420		
								
Add the two equations								
								
0.4	x	+	0	y	=	80		
								
/	0.4							
								
x=		200 $0.15 tickets						
								
plug value of x in (1)								
								
1	x	+	1	y	=	500		
200		+	1	y	=	500		
			1	y	=	500	+	-200
			1	y	=	300		
				y	=	300 $0.25 ticket