How do you solve $x+y=1$ and $x-y=2$ using substitution?

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Answer 1 · 2016-04-11T13:51:57

(1.5, -0.5)

$x+y=1$
$x+y-y=1-y$
So $x=1-y$
Substitute this x-value into the second equation.

$(1-y) -y = 2$

$1-2y = 2$

$1-2y-1=2-1$

$-2y=1$

$(-2y)/-2=1/-2$

$y=-0.5$

Substitute this answer into the original formula

$x+(-0.5)=1$

$x+(-0.5)+(0.5)=1+(0.5)$

$x=1.5$

Check by substituting into the second formula.

$1.5-(-0.5)=2$

$2=2$

How do you solve x+y=1x+y=1 and x-y=2 x-y=2 using substitution?