Question 544372
let the number be xy. x in the tens place.


x+y=6------------(1)

10y+x=4(10x+y)-9
10y+x=40x+4y-9

6y-39x=-9------------(2)

Add equation (1) & (2)

1.00	x	+	1	y	=	6	.............1	
-39	x	+	6	y	=	-9	.............2	
Eliminate 	y							
multiply (1)by 		-6						
Multiply (2) by		1						
-6	x		-6	y	=	-36		
-39	x	+	6	y	=	-9		
Add the two equations								
-45	x				=	-45.000		
/	-45							
x	=	1						
plug value of 			x	in (1)				
x	+		y	=	6		
		+		y	=	6		
				y	=	6		-1
				y	=	5		
				y	=	5		

The number is 15

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