Question 916057
{{{4x+4y=40}}}
{{{-4x-3y=-32 }}}
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STEP 1: 
Find coefficient matrix (D), X matrix (Dx) and Y matrix (Dy). 

In this example we have:

D = {{{(matrix(2,2, 4,4, -4,-3) )}}} 

Dx={{{(matrix(2,2, 40,4, -32,-3) )}}} 

Dy={{{(matrix(2,2, 4,40, -4,-32) )}}} 


STEP 2: Find determinants for D, Dx and Dy. 


det D= {{{(matrix(2,2, 4,4, -4,-3) )}}}={{{4*(-3)-4(-4)=-12+16=4}}}

 det Dx= {{{(matrix(2,2, 40,4, -32,-3) )}}}={{{40(-3)*1-4*(-32)=-120+128=8}}}

 det Dy= {{{(matrix(2,2, 4,40, -4,-32) )}}} ={{{4*(-32)-40*(-4)=-128+160=32}}} 



STEP 3: Solve for the {{{x}}} and {{{y}}} 


{{{x=D(x)/D=8/4=highlight(2)}}} 

{{{y=D(y)/D=32/4=highlight(8)}}} 



 {{{drawing( 600, 600, -5, 10, -5, 10,circle(2,8,.1),locate(2,8,p(2,8)),  graph( 600, 600, -5, 10, -5, 10, -x+10, -(4/3)x+32/3 )) }}}