Question

Jerri needs 3/4 cup of oil and 1 cup of vinegar to make salad dressings. If he only has 2/3 cup of vinegar, how much oil should he use?

Answer 1

if he has 2/3 cup of vinegar he must put 0.4 cup of oil

Answer 2

(3/4) / 1 = x / (2/3).....3/4 oil to 1 cup vinegar = x oil to 2/3 cups of vinegar
cross multiply because this is a proportion
(1)(x) = (3/4)(2/3)
x = 6/12 reduces to 1/2 cup of oil <===