Acupcake recipe calls for 4 cups of flour in order to make 5 dozen cookies. if damiana wants to make 15 dozen cupcakes, how many cups of flour will she need?

Well, if you set a ratio, that would mean 4 cups = 5 dozen. That would mean x cups = 15 dozen. To get from 5 to 15 you multiply 3, so the answer is 100!! NO just kidding, the answer is 4 * 3 = 12

Damiana will need twelve cups of flour.
We know 15/5=3 (3x5=15), so to find how many cups we need we will multiply 4 cups (the amount for 5 dozen) by 3, because fifteen dozen is three times as much as five dozen, which gets us twelve cups. 
So, Damiana will need 12 cups of flour. 
Hope I helped!