Question

what is the value of z in the solution of the system of equations ? 2x+3y-z=12 4x-y+z=-3 -2x+2y+z=3

Answer 1

You have three equations and three unknowns, modify them so they can cancel amongst once another to figure out the solution of each variable.

Answer 2

for example I can add equation#1 to equation#3 to get rid of the "2x" AND "z" and get 5y =15, in which I now have the known number for "y" and can plug back into the equations and solve for the rest.