Solve the Problem $p(x)=90-\frac{x}{8}$ , Then $x C D$ Will Be Sold $x$

Multiple Choice

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

A) $\$ 32,400$
B) $\$ 8100$
C) $\$ 64,800$
D) $\$ 16,200$