A recipe requires 12 cups of flour. You can only measure using 2/3 cups.

How many 2/4 cups are needed for this recipe?

18 cups

Step-by-step explanation:

I assume that the part about 2/4 is an error that really means 2/3.

All you need to do is divide 12 by 2/3. Since you can't divide by a fraction, you have to multiply by its reciprocal, 3/2. You get 36/2, or 18.