Answer:
(z - 1)(x - y)
Step-by-step explanation:
[tex]\begin{array}{rcll}f(x,y,z) & = & z(x - y) + y - x & \\& = &z(x - y) - 1(x - y) & \text{Factored -1 from the last two terms}\\& = & \mathbf{(z - 1)(x - y)} & \text{Factored out (x - y)}\\\end{array}[/tex]
