So, 1 cup is equal to 8 fluid ounces.
1.75 (or 1 3/4) cups is 14 fluid ounces.
You get that answer by multiplying 8 by .75 since you already know that 1 cup is 8 fluid ounces, you need to figure out what the other .75 is.
8 multiplied by .75 is 6. Add 8 and 6 to get 14. Now we know that 1.75 cups is 14 fluid ounces.
Each person drinks 14 fluid ounces and you have 24 people. Multiply 24 by 14 and you get 336.
Your total number of fluid ounces for all 24 people comes out to be 336 fluid ounces.
I hope this made sense and helped you out!