If you have a calculator that can solve linear equations then you can just input these values and get quick answers. If you want to do this manually then one way to do it is to express the first equation (2x - 3y + z = -1) as z(x,y) that is
z= -1 - 2x + 3y
subsitute this equation to eqn 1 and 2 so as to get two equations in terms of x and y.
solve x and y using elimination method and then substitute to the rearranged eqn 1. The values are therefore
x = 1
y = 2
z = 3
