a recipe calls for 1/2 cup of sugar and 3/4 cup of flour. if you have 3 cups of flour and you want to adjust the recipe so you use it all how much sugar do you need?
well lets see, 3/4 cups plus another 3/4 cups totals 1 1/5 cups. double that to make it 3 cups would mean you took the original 3/4 and times it by 4 meaning you would have to take the sugar and times that by 4 as well leaving you with 3 cups of flour and 2 cups of sugar! hopes this helps