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

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Answer 1 · 2016-03-20T05:52:40

$(x, y) = (4, 8)$ $(x,y)=(4,8)$

$x + y = 12$ $color(blue)(x+y=12$

$y = 2 x$ $color(blue)(y=2x$

Substitute the value given for $y$ $y$ in the second equation to the first equation

$\to x + 2 x = 12$ $rarrx+2x=12$

$\to 3 x = 12$ $rarr3x=12$

$\Rightarrow x = \frac{12}{3} = 4$ $color(green)(rArrx=12/3=4$

Substitute the value of $x$ $x$ to the second equation

$\to y = 2 (4)$ $rarry=2(4)$

$\Rightarrow y = 8$ $color(green)(rArry=8$

$color(indigo)( :.ul bar |x,y=4,8|$

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