Question 108316
{{{x+y=-9}}}
{{{x=-y-9}}}


{{{3x-y=-7}}}

but, {{{x=-y-9}}}. So,


{{{3(-x-9)-y=-7}}}
{{{-3x-27-y=-7}}}
{{{-3x-x-27=-7}}}
{{{-4x-27=7}}}
{{{-4x-27+27=-7+27}}}
{{{-4x+0=20}}}
{{{-4x=20}}}
{{{x=-5}}}

Solving for y,

{{{x+y=-9}}}
{{{-5+y=-9}}}
{{{-5+5+y=-9+5}}}
{{{0+y=-4}}}
{{{y=-4}}}


THerefore, x=-5 and x=-4


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HyperBrain!