Carmen Co$.$ can further process Product J to produce Product D$.$ Product J is currently selling for $$22\mathrm{.}90$ per pound and costs $$14\mathrm{.}05$ per pound to produce. Product D would sell for $$43\mathrm{.}60$ per pound and would require an additional cost of $$9\mathrm{.}85$ per pound to produce.The differential cost of producing Product D is