Question 227730
Can someone pls show me how to solve this equation using the addition/elimination process?

1.8x-2y=0.9        Equation A
0.04x+0.18y=0.15   Equation B


Step 1.  Multiply by 0.09 to Equation A to both sides of the equation


{{{0.162x-0.18y=0.081}}}    Equation A1
{{{0.04x+0.18y=0.15}}}    Equation B

Step 2.  Add Equations A1 and B to eliminate the y terms.


{{{0.162x+0.04x-0.18y+0.18y=0.081+0.15}}}


{{{0.202x=0.231}}}


Step 3.  Divide by 0.202 to both sides of the equation


{{{0.202x/0.202=0.231/0.202}}}


{{{x=1.143}}}


Step 4.  Substitute {{{x=1.143}}} into Equation A  {{{1.8x-2y=0.9}}} to solve for y.


{{{1.8*1.143-2y=0.9}}}


{{{2.0584-2y=0.9}}}


Step 5.  Add 2y-0.9 to both sides of the equation


{{{2.0584-2y+2y-0.9=0.9+2y-0.9}}}


{{{1.1584=2y}}}


Step 6.  Divide by 2 to both sides of the equation


{{{y=0.5792}}}


Step 7.  ANSWER:  The solution is {{{x=1.143}}} and  {{{y=0.5792}}}


As a check, use the substitution shown below which have the same results.


*[invoke linear_substitution "x", "y", 1.8, -2, 0.9, .04, .18, .15 ]   


I hope the above steps were helpful.


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Respectfully,
Dr J

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