Shephard's Lemma

Consider a bicycle workshop that services racing bikes. The bicycle workshop produces at the lowest possible cost. Its weekly cost, in dollars, of producing Q services when an hour of mechanic labor costs w dollars and an hour of workstand time costs r dollars is C(w, r, Q) = cfunc. The bicycle workshop pays w = $wage and r = $rent and produces Q = output services a week. How many hours of mechanic labor does the bicycle workshop use per week? Round to two decimals.