Answer:
4x+2(x-6)=12
[tex]4x {}^{2} - 24 + 2x - 12 = 12 \\ 4x {}^{2} - 36 + 2x = 12 \\ 4x {}^{2} + 2x = 12 + 36 \\ 4x {}^{2} + 2x = 48 \\ 4x { }^{2} + 2x - 48 = 0[/tex]