I was thinking thta they had 10 jugs that currently contained 10% water.  I thought there was no paint in the jugs.  That is what they said, 10 jugs that are a gallon in size and have 10% of their volume filled with water.  
So how much water would you have to put in to make those 10 jugs have a ratio of 80/20?  

The way it was worded, to me, left me thinking that they were going to add water and paint to make the 80/20 ratio of those 10 gallons.

I hope that's clear.