For this case we have the following equation:
w = || F || • || PQ || costheta
Where,
|| F ||: force vector module
|| PQ ||: distance module
costheta: cosine of the angle between the force vector and the distance vector.
Substituting values:
w = (60) * (100) * (cos (45))
w = 4242.640687 lb.ft
Answer:
The work done pushing the lawn mower is:
w = 4242.640687 lb.ft