Consider a simple macro model with a constant price level and$$ demand$-$determined output. The equations of the model$$ are: Cequals$=150150$plus$+0\mathrm{.}860\mathrm{.}86$Y$,$ Iequals$=400400,$ Gequals$=750750,$ Tequals$=0,$ Xequals$=150150,$ IMequals$=0\mathrm{.}100\mathrm{.}10$Y$.$ The marginal propensity to spend on national$$ income, z$,$ is$\_\_\_\_\_\_\_\_.$ Question content area bottom Part $1$ A$\mathrm{.}0\mathrm{.}6450\mathrm{.}6450\mathrm{.}645$ B$\mathrm{.}0\mathrm{.}7600\mathrm{.}7600\mathrm{.}760$ C$\mathrm{.}0\mathrm{.}5590\mathrm{.}5590\mathrm{.}559$ D$\mathrm{.}0\mathrm{.}7740\mathrm{.}7740\mathrm{.}774$ E$\mathrm{.}0\mathrm{.}9460\mathrm{.}9460\mathrm{.}946$