Question 893927
Not "ounce"; instead, "FLUID OUNCE".  The measures are by volume.
1 cup = 8 fluid ounces


Olive Oil, 40 cents per fl. oz.
Vinegar, 25 cents per fl. oz.
Wanted, 25% Vinegar.


Already present:  3 cups vinegar, 1 cup olive oil.


How much oil to add?
{{{3(3+1+x)=0.25}}}, using x for how many cups of olive oil to add.
{{{3/(x+4)=0.25}}}
{{{3=(1/4)(x+4)}}}
{{{12=x+4}}}
{{{x=8}}},  Add 8 cups of oil.


Cost of this vinegarette?
3 cups vinegar + 9 cups oil.  This is 12 cups.

{{{3*8*40+9*8*25=24(40+25)=24*65}}} cents
{{{1560}}} cents
$15.60