The total is the 100% and that is 27000, the question is what percentage is 4865
We can use a simple rule of three, direct proportion to solve:
27000 ft^3 --------> 100%
4865 ft^3 ---------> x
x =(4865)(100)/27000
x = 18.02
therefore 4865 ft^3 is 18.02% of 27000 ft^3
