The cost c of printing a magazine is jointly proportional to the number of pages p in the magazine and the number of magazines printed m. (use k for the constant of proportionality.)

(a) write an equation that expresses this joint variation.

(b) find the constant of proportionality if the printing cost is $65,550 for 3800 copies of a 115-page magazine.

(c) how much would the printing cost be for 3500 copies of a 84-page magazine?