Answer:
If you removed the ounces of vinegar to 7.5, it'd be 25% vinegar.
If you add 7.5 ounces oil, then it'd be the same thing, I believe.
I am getting confused by the part with the "n"
"A mixture of 12 ounces of vinegar and oil is 40% "n" vinegar by weight"
Explanation:
So you have 12 ounces of vinegar, and it's 40%.
You need to get this 40% to be 25%... So how many ounces do you need to remove....