Answer
$16, 245 ft-lbs $
Work Step by Step
The magnitude of gravitational force acting on the man +Can of paint $=(160+m)lbs$
In the upward direction, we get
$F \cdot dr=(185-\dfrac{9r}{s}) dr$
$W=\int_C F\cdot dr= \int_0^s (185-\dfrac{9r}{s}) dr$
Here, $C$ shows a vertical line segment connects the bottom and top part of the silo.
Now, we have $W=\int_C F\cdot dr=[185r-\dfrac{9r^2}{2s}]_0^s=185 s-4.5 s =16, 245 ft-lbs $
