A cookie recipe states for every three cups of flour, 1 teaspoon of vanilla are needed. how many teaspoons are needed for five cups of flour?

For 3 cups ... vanilla needed - 1 teaspoon

for 1 cup ... vanilla needed - 1/3 teaspoon

for 5 cups, vanilla needed - 5/3 teaspoon

In short, 1.67 or 5/3 teaspoon of vanilla is needed for 5 cups of floor