The answer to your question which was .....Find the unit price. Round your answer to the nearest cent if necessary, and do not include units or the dollar sign in your answer.
24-pack of juice boxes for $6.99
So since you said that For every 24-pack of juice is for $6.99
There are actually 2 answers, 3 and -3. Although if you put it in a calculator, it would show "math error" or undefined. That's because the index is even (4) and the radicand is negative (-81)