\left[ {\begin{array}{*{20}c}
   X_1 - 3X_3 & X_2 - 3X_4  \\
   14X_1 + 3X_3 & 14X_2 + 3X_4  \\

 \end{array} } \right]= 
 \left[ {\begin{array}{*{20}c}
   0 & -2  \\
   5 & 5  \\

 \end{array} } \right]