The number of cups of brown sugar that are needed for each egg is 1 cup.
What is the number of cups?
To determine the amount of brown sugar needed for each egg, we would do a division calculation that simplifies the ratio of brown sugar to eggs. It can be analyzed this way;
Brown sugar per egg = Total brown sugar / Number of eggs
Brown sugar per egg = 4 cups / 4 eggs
Brown sugar per egg = 1 cup
Therefore, 1 cup of brown sugar is needed for each egg in Mom's cookie recipe as seen in the simplification above.