How do you solve the system by substitution $x + y = 12$ and $y = 2x$ ?

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Answer 1 · 2016-10-01T14:20:41

Solution is $x=4$ and $y=8$

We have two equations $x+y=12$ and $y=2x$

Let us substitute value of $y$ from second equation in the first equation.

As $y=2x$ , substituting this in first we get

$x+2x=12$

or $3x=12$

or $x=12/3=4$

and hence $y=2x=2xx4=8$ , therefore

Solution is $x=4$ and $y=8$

How do you solve the system by substitution x + y = 12x + y = 12 and y = 2xy = 2x?