Shares of ACME Corp. are currently trading for $$15.$ Call options on ACME Corp. shares, which expire in six months with a strike price of $$25,$ are trading for $$7\mathrm{.}5.$ A trader writes one call option contract. Assume that there is one share per contract. At maturity, what is the payoff to the call option writer if the stock price is $$45?$