$6-39.$

a$.$ Compare the probable part cost from Machine $\backslash ($ A $\backslash )$ and Machine $\backslash ($ B $\backslash ),$ assuming that each will make the part to the same specification. Which machine yields the lowest part cost? Assume that the MARR $\backslash (=10\backslash \%\backslash )$ per year. $(6\mathrm{.}5)$

b$.$ If the cost of labor can be cut in half by using part$-$time employees, which machine should be recommended? $(6\mathrm{.}5)$