To make exactly 20 servings, we need to know how much honey is used for exactly one serving.
Given that 1/3 cup of honey equates to 8 servings, divide 1/3 by 8 to get the amount of honey needed for 1 serving.
Then, to figure out how much honey is needed for 20 servings, simply multiply that result by 20.
Hope this helps!
-refrac532