Question 515166
add the 1st and 2nd eqns to eliminate x ___ y - 2z = 1 (A)


add the 1st and 3rd eqns to eliminate x ___ 7y - 13z = 3 (B)


multiply eqn (A) by -7 and add to eqn (B) to eliminate y ___ z = -4


substitute back to find x and y