Question 148094
{{{x+y=-12}}}
{{{x-y=-4}}}

Since the y's in the expressions  are opposites, then just add the expressions to each other to eliminate the y variable from the jump.  


  {{{x+y=-12}}}
+{{{x-y=-4}}}
----------------
 {{{2x =-16}}}


Then divide both sides by 2
{{{x=-8}}}


Then to get y, plug x back into one of the original equations {{{x+y=-12}}} or
{{{x-y=-4}}}. Doesn't matter which one.  How about {{{x+y=-12}}}.  


Plug in -8 for x
{{{-8+y=-12}}}.  


Then add 8 to each side
{{{y=-4}}}.


Plug both values into the other original equation {{{x-y=-4}}}. 
{{{-8--4=-4}}} or {{{-8+4=-4}}}. It's true.


Therefore,
x=-8
y=-4