Answer: For 1 cup of flour, there should be 6 teaspoons of vanilla.
Step-by-step explanation:
What I did is that I found what 1 ÷ 2/3 equals. To find that, I used the reciprocal so the new equation would be 1 × 3/2 which equals 3/2. So since 2/3 × 3/2 equals 1, we have to do the same to 4 teaspoons. 4 × 3/2 equals 6. Therefore, there should be 6 teaspoons of vanilla for every one cup of flour.
Hope this helps! Don't hesitate to ask for clarification.