The manager of a CD store has found that if the price of a CD is $p(x)=90-\frac{x}{8},$ then $CD$ s will be sold. Find an expression for the total revenue from the sale of $xCD$ s $($hint reverue $=$ demand $$ price$).$ Use your expression to determine the maximum revenue.

$$16,200$

$$8100$

$$32,400$

$$64,800$