Answer:
22 gallons
Explanation:
First make the fractions match by finding a common denominator so they are easier to hand. 1/6 can be used as the common denominator so you'll have to convert 2/3. Multiply the top and bottom by 2 and you'll have 4/6.
So now you know by adding 11 gallons, you ended up with a total of 4/6 of a full container. If you subtract off what was in the tank originally ( 1/6 ), you'll know how much of the tank got filled with the 11 gallons.
4/6 - 1/6 = 3/6 3/6 is equal to 1/2
So now you know 11 gallons is equal to 1/2 of the container.
So the tank will hold twice as much as that or 22 gallons.