The recipe calls for
1/2 cup of sugar : 1 cup of flour : 1/3 cup of milk for 1 batche
We need to make 3 batches, so
Multiply each ingredient bu 3
Sugar = 1/2 * 3 = 3/2 cups
Flour = 1 * 3 = 3 cups
Milk = 1/3 * 3 = 1 cup
3/2 cups of sugar : 3 cups of flour : 1 cup of milk