To make key chainkey chain$$s$,$ there is an initial$$ set$-$up cost of $$$$873873.$ It also costs $$$$0\mathrm{.}210\mathrm{.}21$ per key chainkey chain for materials and labor.$$

$$a$.)$Letting x represent the number of key chainkey chains $$made$,$ what will be the total cost function$$ C$($x$)?$

$$C$($x$)=$ enter your response here

$$b$.)$If we sold each key chainkey chain for $$$$0\mathrm{.}580\mathrm{.}58,$ what will be the total revenue function$$ R$($x$)?$

$$R$($x$)=$ enter your response here

$$c$.)$What is the smallest number of key chainkey chains needed to be sold in order for the total revenue to be at least the total cost necessary to make$$ them?

enter your response here key chainkey chains