$3.$Sienna has contracted out some of the Marketing of her store to a telemarketing company, CoolCalls. She pays a monthly flat $$735$ per month for this service, plus a commission of $3\mathrm{.}5\%$ of all sales greater than $$15,500$ that have been linked to CoolCalls efforts. If CoolCalls generated $$45,900$ last month, what was the total cost for their service?