Solve the Problem $x$ Units of Perfume Is $C(x)=(6 x+5)(3 x+9)$ Find the Marginal Average Cost Function

Solve the problem.
-The total cost to produce $x$ units of perfume is $C(x) =(6 x+5) (3 x+9)$ . Find the marginal average cost function.

A) $18 x+69+\frac{45}{x}$
B) $36-\frac{69}{x}$
C) $18-\frac{45}{x^{2}}$
D) $36 x+69$