Use a calculator x 2y - z 7 2x - 3y - 4z -3 x y z 0. Suitable for both leaving cert higher level and leaving cer. Solving a System of 3 Equa.
Use rows one and three to create the second zero in row three.
Do that by eliminating one of the unknowns from two pairs of equations. Suitable for both leaving cert higher level and leaving cer. 2 - 3z 4 z -23. 4 3x 4y 11.