Question 160345
dividing 3rd eqn by -2 gives NEW 3rd eqn __ x+y-3z=122


new 3rd eqn times 3, added to 1st eqn __ 4y+2z=-44 __ 2y+z=-22


new 3rd eqn times 4, added to 2nd eqn __ -2y-7z=274


adding eqns __ -6z=252 __ z=-42


substituting __ 2y+(-42)=-22 __ y=10


substituting __ x+(10)-3(-42)=122 __ x=-14