For the Fruit punch
Yasmin uses 4 cups of papaya juice for every 6 cups of pine apple juice
i.e.

Since, Yasmin has already 24 cups of juice, then for the number of cups of Papaya juice, we multiply the number of Papaya cups reuquire for 1 cup of pineapple juice by 24.

So, for the fruit punch,
16 Cups of Papaya juice needed for 24 cups of Pineapple Juice.
Answer :
16 Cups of Papaya juice