Answer:
B) f = (6 x 8) + 4
Explanation:
Remember this: 1 cup = 8 fl oz
They're asking for the total number of fluid ounces of detergent, and we're given 6 cups and 4 fl oz.
Set up a proportion to find the total number of fl oz from the 6 cups, let variable x be the total oz of the 6 cups:

The answer should be 48 fl oz, then you add the 4 fl oz to have the total of 52 fl oz.
SORRY just wanted a full break down of the problem solved. I made it too complex than it's supposed to be. Hope my answer helps a bit. :)