Question 489751
(1) {{{3x - 6y = 18}}}
(2) {{{6x - 2y = -12}}}
Divide both side of (1) by {{{ -3 }}}
and add the equations
(1) {{{-x  + 2y = -6}}}
(2) {{{6x - 2y = -12}}} 
{{{ 5x = -18 }}}
{{{ x = -18/5 }}}
and
(1) {{{-x  + 2y = -6}}}
(1) {{{ 18/5 + 2y = -6 }}}
Multiply both sides by {{{5}}}
(1) {{{ 18 + 10y = -30 }}}
{{{ 10y = -48 }}}
{{{ y = -24/5 }}}
Here's a plot of the equations:
The intersection looks like (-18/5, -24/5)
{{{ graph( 400, 400, -10, 10, -10, 10, (1/2)*x - 3, 3x + 6 ) }}}