Step 1 :First, we represent the system of equations in matrix form. The matrix A is \[\begin{bmatrix} 5 & 4 & -5 \\ 3 & -5 & 3 \\ 6 & -3 & 6 \end{bmatrix}\] and the matrix B is \[\begin{bmatrix} -35 \\ 10 \\ -15 \end{bmatrix}\].
Step 2 :We then solve the system of equations using the matrix method. The solution is \[\begin{bmatrix} -4 \\ -5 \\ -1 \end{bmatrix}\].
Step 3 :Finally, we can conclude that the solution to the system of equations is \((-4, -5, -1)\). Therefore, the correct choice is A. The solution set is \(\boxed{\{(-4, -5, -1)\}}\).