Using $6$ baristas $($L $)=(6)$ and $3$ espresso makers $($K $)=(3),$ The Beet Box Cafe produces an output of Q$^(**),$ as shown in the accompanying diagram. a$.$ A fall in the rental rate on espresso machines, R $,$ will cause the marginal product per dollar spent on labor, $($MP$\_($L$))/($W$),$ to the marginal pro