The fruit salad recipe requires 1/3 cup of strawberries and the smoothie recipe requires 3/4 cup of strawberries. So in total, 1/3 + 3/4 = 5/12 cup of strawberries are required for both recipes.
Now we know that Cindy and Borling are both making the recipes. So we need to multiply the 5/12 cup of strawberries by 2 to find out how many cups of strawberries are needed for both of them.
5/12 cup * 2 = 10/12 cup or 5/6 cup of strawberries.
Now if two more friends are joining them, we need to multiply the 5/6 cup of strawberries by 4 to find the total number of cups of strawberries required for all 4 of them.
5/6 cup * 4 = 2 and 1/6 cups.
So in total, 2 and 1/6 cups of strawberries would be required for both girls and two of their friends.