12x = 54 - 6y.....multiply by -1
-17x = -62 - 6y
-----------------
-12x = -54 + 6y (result of multiplying by -1)
-17x = -62 - 6y
-----------------add
-29x = - 116
x = -116/-29
x = 4
12(4) = 54 - 6y
48 = 54 - 6y
48 - 54 = -6y
-6 = -6y
-6/-6 = y
1 = y
solution is (4,1)