Step 1

$ \Delta = \begin{vmatrix} 2 & 3 \\ 4 & 6 \end{vmatrix} = 12-12=0$

The system may or may not be consistent.

Step 2

$ \Delta x = \begin{vmatrix}5 & 3 \\ 12 & 6 \end{vmatrix} = 30-36 = -6 \neq 0$

$ \Delta = 0$ but $ \Delta x \neq 0.\: \: \therefore$ the system is inconsistent and has no solution.