The y variable stands for the y value in an equation like x+y=1
9/27, 12/27, 16/27
So this is a geometric sequence as each term is 4/3 the previous term.
Since the common ration is greater than one the sum of the series diverges, it does not exist. (The sum just keeps getting larger and larger)
For a geometric series to have a sum r^2<1
So that the normal sum....
s(n)=a(1-r^n)/(1-r) becomes if r^2<1
s=a/(1-r)
If he only filled up five containers, then he would only have one and 1/4 gallons of oil