Help, help, help! Dosage calc ?

Okay, here is the question. Dr orders 3/4 strength tube feeding. Prepared formula comes in cans containing 240 ml. How much water will you need to add to the formula to make a 3/4 strength solution.

Here is my answer... 3/4 x 240 =180 ml of solution. 240-180= 60 ml of water to add.

BUT, my instructor says the answer is 80 ml. We tried to get her to show us how she got that, but she just said 80 is the answer. HELP! I am not seeing how she got that at all!

Your instructor is correct..............

Why are you going to throw 25% of the feeding out? That is what you will be doing, if you do it your way. You want to add water to the 240 ml amount of feeding that you have, not throw part of it out. So you want to divide the 240 ml by three and that gives you 80 for the other part that is water added. You just need to add what that third was and it will give you 320 ml, that would be the total amount.