Question 416688
$20 bill - x numbers
$50 bill - y numbers
x+y = 37 

20x+50y =1100

x+y=37	.............1	
20x+50y	=1100.............2	
								
multiply (1)by 					-20			
Multiply (2) by					1			
-20x-20y=-740		
20x+50y	=1100		
								
Add the two equations								
								
30y=360		
/30							
								
y=12 $30 bills					
Plug value of y in 							
x+y=	37		
x+12=37		
x=25	$20 bills