8÷2=4 so only you will only need 1 cup of flour for 4 servings. now when you divide that 1 cup into 4 servings. only 1/4 cup of flour would be needed for 1 servings. add that 1/4 cup to the amount of 5 servings. so you will need 1 1/4 cups of flour for 5 servings