Answer:
about 1099 pounds
Explanation:
The weight of the truck is directed downward. It is countered by a force normal to the plane of the hill and one that is parallel to the plane of the hill. The question is asking about this latter force.
The magnitude of the force parallel to the hillside required to keep the truck stationary is ...
(2600 lb)·sin(25°) ≈ 1098.81 lb ≈ 1099 lb