Answer: C
Step-by-step explanation: As you most likely know, the matrix represents the system of equations. If you assume that x is the far left column, that y is the column adjacent to it, and that y is to the left of the line, you can assume that these are the equations represented:
1x-3y+2z=-9
1x+0y+1z=1
0x+2y-1z=7
which can be simplified to
x-3y+2x=-9
x+z=1
2y-z=7
