Two sample of Oleum are labelled as 109% and 115%,what is the difference between weight of free SO3 in these samples ?.

Given % labelling (X)=109%  and 115% ,finddifference between weight of free SO₃ in these samples ?. 

 Difference between weight of free SO₃ in these samples are= 66.66-44= 26.67 gm