You need to write the augumented matrix of the linear system. Since the system has three equations and three variables, the square matrix of system of linear equations looks like:

A = `((2,3,-5),(7,0,3),(3,-6,1))`

The number of rows of the matrix corresponds to the number of equations, whilst the number of columns corresponds to the number of variables in equation.

The augumented matrix hosts the column of the terms from the right side of the equal sign.

A_1 = `[[2,3,-5,1],[7,0,3,7],[3,-6,1,-5]]`