Guzie's cookie recipe it says to use 2 ⅓ cups of flour to ¼ cup of brown sugar. How much brown sugar would you use per cup of flour?

So, per every 7/3 cups of flour, 1/4 cup of brown sugar is required.

For 1 cup of flour, 1/4 * 3/7 cup of brown sugar would be required, that is, 3/21 cups of brown sugar.