Stephanie has a recipe that calls for 2/3 tablespoon of vanilla to make 3 1/2 dozen cookies. How many tablespoon of vanilla are needed per dozen cookies.
4 / 21 spoonful of vanilla Step-by-step explanation: 3 1/2 dozens = 42 cookies Let x = spoonful of vanilla for 1 dozen of cookies 2/3 : 42 cookies x : 12 cookies 2/3 ÷ 42 = x ÷ 12 2/3 × 1/42 = x / 12 2 / 126 = x / 12 Cross product 2*12 = 126*x 24 = 126x Divide both sides by 126 x = 24 / 126 = 4 / 21 x = 4 / 21 spoonful of vanilla Per dozen of cookies requires 4/21 spoonful of vanilla Check: 4/21 per dozen × 3 1/2 dozens 4/21 × 7/2 28 / 42 2/3 spoonful for 3 1/2 dozens
