The Demand for Rubies at Royal Ruby Retailers Is Given $q = - \frac { 4 } { 3 } p + 80$

Short Answer

The demand for rubies at Royal Ruby Retailers is given by
$q = - \frac { 4 } { 3 } p + 80$
where p is the price RRR charges (in dollars) and q is the number of rubies RRR sells per week. At what price should RRR sell its rubies to maximize its weekly revenue

Please enter your answer in dollars without the units.