I understand that B is the right answer because you can get a number out of it, but how would i set up the equation to relate to the statement?

Thanks.

You're right that you don't actually need to do this on a data sufficiency - but on the chance that you get one that looks like this one and it's not a data sufficiency question, here's how you'd set it up.

half of the bucket = x/2
1/3 of that is 1/3 * x/2 or x/6.
So when we say that it will increase by 1/3, we mean that it will become x/2 + x/6.
Thus x/2 + 3 = x/2 + x/6
Simplified:
3 = x/6
x = 18

Make sense?

Veritas Help

Sure does, thank you!