The Work Done by a Variable Force $F ( x ) = 40 - x$

Multiple Choice

The work done by a variable force $F ( x ) = 40 - x$ Newtons that moves an object along a straight line in the direction of F from x = 5 meters to x = 20 meters, in Newton-meters, is

A) $\frac { 825 } { 3 }$
B) $\frac { 655 } { 3 }$
C) $\frac { 825 } { 2 }$
D) $\frac { 655 } { 2 }$
E) $\frac { 723 } { 3 }$