6x - y = -5      (1)
6x + y = -7      (2)


From eq(2),  express  y = -7 - 6x  and substitute it into equation (1). You will get


6x - (-7-6x) = -5,


6x + 6x + 7 = -5

12x = -5 - 7 = -12  ====>  x =  = -1.


Now substitute this value of x into eq(2) to get


{{6*(-1) + y}}} = -7,    or

-6 + y = -7

y = -7 + 6 = -1.


Answer.  The solution is  x= -1;  y= -1.


    Check the solution on your own by substituting the found values into the original equations.

    Do it on your own (I just did it mentally).