Torque Example Problem lever arm horse on wall

Suppose a horse leans against a wall as shown. Calculate the force exerted on the wall assuming that force is horizontal while using the data in the schematic representation of the situation. Note that the force exerted on the wall is equal in magnitude and opposite in direction to the force exerted on the horse, keeping it in equilibrium. The total mass of the horse and rider is 500 kg. Take the data to be accurate to three digits.(Problem adapted from OpenStax)

[@spagomat]

Thank you, this really helped me understand 'line of action' (which is never defined in the Openstax book).