Here is the continuation to the question ; The buoyant force is the difference between the fluid forces on the top and bottom of the solid. (The weight-density of water is 62.4 pounds per cubic foot.)
We need to find the difference first. 65 - 60 = 5. Now we must find what percent 5 is of 65. It is 7,7%. The number decreased, and so it is a 7,7% decrease.