$9\mathrm{.}6$ For the following optimization formulation: minx$+$y$+$z $,2$x$-5$y$=5$ z$<=$x$+20<=$x$+$y$+$z Is the formulation linear or nonlinear? Is the formulation convex or nonconvex? Why? Is the problem a LP QP Convex NLP Nonconvex NLP MILP Other