To solve this problem, we must first figure out how many ounces of the mixture Barbara makes total, and then divide this amount by 6 (because there are 6 ounces per serving).
To find out how many ounces of the mixture Barbara makes, we must add together the ounces of granola (54) and the ounces of raisins (36).
54 + 36 = 90
Next, we should divide this amount by the number of ounces per serving (6).
90/6 = 15
Therefore, Barbara makes 15 servings.
Hope this helps!