Answer
$2400 (cos 40 ^\circ) \approx 1839$ ft-lb
Work Step by Step
Horizontal component of the force is: $|F|cos 40 ^\circ$
$F=30 lb$
and
$d =80 ft$
As we know the work done is calculated as:
$ W=| F||d| cos 40^\circ$
Thus,
$ W=( 30 lb) (80 ft) (cos 40 ^\circ)$
$W= 2400 (cos 40 ^\circ) \approx 1839$ ft-lb
