loss matrix for B

A \left [ \begin{matrix} 7 & 9 & 8 & 10 \\ 12 & 1 & -2 & -3 \\ 5 & 5 & 6 & 9 \\10 & 6 & -3 & -4 \end{matrix} \right]

Using dominance property i got a 3x2 matrix as

\left[ \begin{matrix} 7 &  8 & 10 \\ 12 & -2 & -3 \end{matrix} \right]

and my graph with equations

7x_1 + 12x_2 \geqslant V
8x_1 - 2x_2 \geqslant V
10x_1 - 3x_2 \geqslant V

Game Theory - graphical method-imag0692.jpg

so the highest intersection point 2x2 matrix is with 1st and 2nd columns from the 3x2 matrix

\left[ \begin{matrix} 7 & 8 \\ 12 & -2 \end{matrix} \right] is this correct or is there something wrong in my graph.