Mary is baking a cake. The recipe calls for 18 cups of flour and 415 cups of sugar. She already put in 17 cups of flour. How many more cups of sugar than cups of flour does she need to add now?
1. Mary has already put in 17 cups of flour. 
2. The recipe calls for 18 cups of flour. 
3. So, Mary needs to add 1 more cup of flour. 
4. The recipe calls for 415 cups of sugar. 
5. So, Mary needs to add 415 - 17 = 398 more cups of sugar.