An electronic toy company has compiled data based on their records of annual sales. They have found a relationship between the sales of one toy and that toy’s price: $\displaystyle{q}=-{5}{s}+{1300}\usepackage{cmbright}\Huge\$ , where q=quantity sold and s=selling price of the item. The cost to produce each toy is $80.

Using the Profit formula P = Total Revenue - Production Costs (in this case, $\displaystyle{P}={s}{q}-{80}{q}\usepackage{cmbright}\Huge\$ ), identify which equation could be used to find the selling price, s, that produces the maximum profit.