Alright, so ethan’s cookies would be 21 cookies per 3 cups of sugar. So you would do 21/3 to find you get 7 cookies per one cup of sugar
Then Mias cookies are 24 cookies per 4 cups of sugar. You would do 24/4 to get 6, so 6 cookies per cup of sugar. 
Mia’s cookies make less cookies per cup of sugar, so they’d have more sugar in them. 
Mia- 6:1 
Ethan- 7:1