Question 583654
{{{7x-4y=-30}}}..........(1)
{{{3x+4y=10}}}..........(2)
Add (1) and (2)
{{{7x-4y=-30}}}
{{{3x+4y=10}}}
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{{{10x=-20}}}
{{{cross(10)x/cross(10)=cross(-20)/cross(10)}}}

{{{x=-2}}}
Put the value of x in (2)
{{{3x+4y=10}}}..........(2)
{{{3(-2)+4y=10}}}
{{{-6+4y=10}}}
{{{4y=10+6}}}
{{{4y=16}}}}
{{{4y/4=16/4}}}
{{{cross(4)y/cross(4)=cross(16)/cross(4)}}}
{{{y=4}}}
x,y=-2,4


Check
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Put the value of x and y in (1)

{{{7x-4y=-30}}}..........(1)
{{{7(-2)-4(4)=-30}}}
{{{-14-16=-30}}}
{{{-30=-30}}}
Put the value of x and y in (2)
{{{3x+4y=10}}}..........(2)
{{{3(-2)+4(4)=10}}}
{{{-6+16=10}}}
{{{10=10}}}