Question 245385
1.{{{x + 7y = -2}}}
2.{{{3x + y = 34}}}

From 2,
{{{3x+y=34}}}
{{{y=34-3x}}}
Substitute into eq. 1,
{{{x+7(34-3x)=-2}}}
{{{x+238-21x=-2}}}
{{{-20x=-240}}}
{{{x=12}}}
From eq. 1,
{{{x+7y=-2}}}
{{{12+7y=-2}}}
{{{7y=-14}}}
{{{y=-2}}}
(12,-2)
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{{{-4x + 9y = 20}}}
{{{-2x - 2y = 10 }}}
Multiply eq. 2 by -2 and add to eq. 1
{{{-4x+9y+4x+4y=20-20}}}
{{{13y=0}}}
{{{y=0}}}
From eq. 2, 
{{{-2x-2y=10}}}
{{{-2x=10}}}
{{{x=-5}}}
(-5,0)