in easiest terms subtract 1/2 cups of water until you cant take 1/2 cups out. then you see how much more you need to take out then do the math. in this case you need to take out 1/4 cups more out until you have nothing left. if you can visualize this in your head you know that 1/4 is 1/2 of 1/2 so you take out half as much as you did before.
