Question 681834
1.{{{2x+2y=12}}}
   {{{x+y=6}}}
2.{{{x=2y}}}
Substituting 2 in 1 and solve for y
{{{x+y=6}}}
{{{2y+y=6}}}
{{{y=2}}}
y=2 in 1
{{{x+y=6}}}
{{{x+2=6}}}
{{{x=4}}}