Which proportion could you use to convert 64 fluid ounces to cups?

To convert fluid ounces to cups, you can use the proportion:

1 cup / 8 fluid ounces = x cups / 64 fluid ounces

Cross multiplying the equation, we get:

8 fluid ounces * x cups = 1 cup * 64 fluid ounces

8x = 64

Dividing both sides of the equation by 8, we find:

x = 8

Therefore, the proportion to convert 64 fluid ounces to cups is 8 cups / 64 fluid ounces.