### Moment of Force Exerted in Mechanics

I'm having some trouble understanding how to get to the answer. The answer is in the book. -( 25.4 lb x ft)i - ( 12.60 lb x ft) j - ( 12.60 lb x ft) k . A 6- ft- long fishing rod AB is securely anchored in the sand of a beach. After a fish takes the bait, the resulting force in the line is 6 lb. Determine the moment about A