Answer:
22.5 lbs
Explanation:
First you find the cubic feet. That is the volume of the object which is length*width*height.
In your example, they are using inches. So you have to convert all units to feet. That would be 0.5 inches, 0.5 inches, and 5/3 inches. The volume would be 0.5*0.5*5/3 which is about 5/12 cubic feet
You then take that 5/12 cubic feet and multiply it by the 54 lbs/cubic foot. The answer would be 22.5 lbs