2x - 6y = 14
2x = 6y + 14
x = 3y + 7.....so sub in 3y + 7 for x in the other equation
4x - y = 9
4(3y + 7) - y = 9
12y + 28 - y = 9
12y - y = 9 - 28
11y = - 19
y = -19/11
x = 3y + 7
x = 3(-19/11) + 7
x = -57/11 + 7
x = -57/11 + 77/11
x = 20/11
solution is : (20/11, -19/11) <==
