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How do you solve $x + y = 12$ $x + y = 12$ and $y = 2 x$ $y = 2x$ using substitution?

1 Answer

Jun 17, 2016

x=4; y=8

Explanation:

You can substitute the value of y variable (y=2x) in the first equation:

$x + 2 x = 12$ $x+2x=12$

and symplify:

$3 x = 12$ $3x=12$

$x = \frac{12}{3} = 4$ $x=12/3=4$

let's put this value in the second equation, so

$y = 2 (4) = 8$ $y=2(4)=8$

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