The Ordering and Transportation Cost C for the Components Used $C = 160 \left( \frac { 280 } { x ^ { 2 } } + \frac { x } { x + 40 } \right) , x \geq 1$

The ordering and transportation cost C for the components used in manufacturing a product is $C = 160 \left( \frac { 280 } { x ^ { 2 } } + \frac { x } { x + 40 } \right) , x \geq 1$ where $C$ is measured in thousands of dollars and $x$ is the order size in hundreds. Find the rate of change of $C$ with respect to $x$ for $x = 24$ . Round your answer to two decimal places.

A) $- 6.44$ thousand dollars per hundred
B) $8.04$ thousand dollars per hundred
C) $3.28$ thousand dollars per hundred
D) $- 4.92$ thousand dollars per hundred
E) $- 7.96$ thousand dollars per hundred