hi :)
1 gallon of milk is equal to 16 cups of milk.
If 1 1/4 cups of milk are used to make 10 servings, then 1 cup of milk will be used to make 10/(5/4) = 8 servings.
Therefore, 16 cups of milk will be used to make 16 x 8 = 128 servings.
So, 1 gallon of milk can be used to make 128 servings.