Just multiply 110.25 grams of brown sugar by 4.5 batches to get 496.125 grams of brown sugar. I don't mind answering these questions for points, but I am a little concerned that you don't know how to do this.
Explanation: Recipe calls for 110.25 g of brown sugar + 55.45 g for the topping. 1 recipe = 110.25 + 55.45 1 recipe = 165.60 g Len is making 4.5 batches, so 165.60 • 4.5 = 745.2 g of brown sugar.