Solve the Problem $x$ Items Is Given By $P(x)=\frac{3 x+6}{7 x+8}$ Find the Marginal Average Profit Function

Solve the problem.
-The total profit (in hundreds of dollars) from selling $x$ items is given by $P(x) =\frac{3 x+6}{7 x+8}$ . Find the marginal average profit function.

A) $\frac{66}{(7 x+6) ^{2}}$ hundreds of dollars per item
B) $\frac{-18}{(7 x+6) ^{2}}$ hundreds of dollars per item
C) $\frac{-21 x^{2}-84 x-48}{\left(7 x^{2}+8 x\right) ^{2}}$ hundreds of dollars per item
D) $\frac{-21 x^{2}-90 x-48}{\left(7 x^{2}+8 x\right) ^{2}}$ hundreds of dollars per item