The Demand Function for a Certain Commodity Is $p ( x ) = \frac { 1800 } { ( x + 5 ) ^ { 2 } }$

Multiple Choice

The demand function for a certain commodity is $p ( x ) = \frac { 1800 } { ( x + 5 ) ^ { 2 } }$ . Find the consumer surplus when the selling price is $18?

A) 135
B) 30
C) 45
D) 360
E) 270
F) 40
G) 90
H) 180