2x + 4y = 14.....multiply by -3
3x + 12y = 51
----------------
-6x - 12y = - 42 (result of multiplying by -3)
3x + 12y = 51
----------------add
-3x = 9
x = -9/3
x = -3
2x + 4y = 14
2(-3) + 4y = 14
-6 + 4y = 14
4y = 14 + 6
4y = 20
y = 20/4
y = 5
solution is (-3,5)