-6x + y = - 4 / + 6x ;
y = 6x - 4 ;
We substitute y in first equation : -5x + 3( 6x - 4 ) = 12;
-5x + 18x - 12 = 12 ;
13x - 12 = 12 ;
13x = 24 ;
x = 24 / 13 ;
y = 6*(24 / 13 ) - 4 ;
y = 144 / 13 - 4 ;
y = 144 / 13 - 52 / 13;
y = 92 / 13 ;
The solution is x = 24 / 13 and y = 92 / 13 ;