Hokey Min's Kleen Karpet cleaned $85$ rugs in October, consuming the following resources:

$\backslash$table$[[$Labor:$,520$ hours at $$15$ per hour$],[$Solvent:$,120$ gallons at $$5$ per gallon$],[$Machine Rental:,$24$ days at $$75$ per day$]]$

a$)$ Labor productivity per dollar $=$ rugs$/$dollar $($round your response to four decimal places$).$