We know that
To know the number of 1/2 cup portions will make this recipe, we have to transform 10 gallons into cups. It's important to know that 1 gallon is equivalent to 16 cups. So, 10 gallons are 160 cups.
So, if each portion is 1/2 cup, then we would have 320 cups, that is, the cups would double.
Therefore, the recipe makes 320 portions of 1/2 cups.