we are solving this under the assumption that pure oil is being added to the 3.2% solution, but this needs to be specified in the problem statement!

let 'x' represent the total amount of fuel after adding in some 3.2% fuel and let 'y' represent the pre-existing amount of 3.2% fuel

concentration = pure/total

let 'p' represent the amount of pure oil already in the 3.2% fuel:

0.032 = p/y, so p = 0.032y

we want a 5.5% solution:

0.053 = (x+0.032y)/(x+y)

solving for 'x' we have:

x = (21y)/947

x = 0.022y

we need to add approximately 0.22y of pure oil, where 'y' is the amount of existing fuel