We have a matrix with 3 rows and 4 columns. Each row represents an equation of the linear system. The first 3 elements from left to right represent the coefficients of our variables, and the last element on the row represents the right side of the equality.
From the first row, we have the following equation
[tex]\begin{gathered} 4\cdot x+0\cdot y+3\cdot z=-15 \\ 4x+3z=-15 \end{gathered}[/tex]
