safety factor in a cantilevered beam bracket?
12 inches and 100 pounds gives you a moment of 1200 lb-inchs. With a safety factor of 5 the bracket must be able to support a torque of 6000 lb-inches. If you have a load suspended at 18 inches and 72 lbs, the torque is now 1296 lb-in. max strength of the bracket is still 6000 lb-inches therefore your new safety factor is 6000/1296 or 4.6296 or 4.6