Final answer:
Ruby needs a total of 13 cups of combined powdered milk and whole wheat flour.
Step-by-step explanation:
To find out how many combined cups of powdered milk and whole wheat flour Ruby needs, we first need to find out how much of each ingredient is needed for one batch of pancakes.
The recipe calls for 1/4 of a cup of powdered milk and 3 cups of whole wheat flour. So, for one batch of pancakes, the total combined cups of powdered milk and whole wheat flour is 1/4 + 3 = 3 1/4 cups.
Since Ruby plans on making four batches of pancakes, she would need a total of 4 x 3 1/4 = 13 cups of combined powdered milk and whole wheat flour.
Therefore, the combined cups of powdered milk and whole wheat flour Ruby needs is 1 cup of powdered milk plus 12 cups of whole wheat flour, which equals 13 cups combined.