How can you use a rate to compare the costs of two boxes of cereal that are different sizes?

Let's say you had two boxes of cereal labeled A and B. Also let's come up with a hypothetical situation that...

The question is: which is the better deal? By that I mean which is cheaper per ounce.

For box A, we have this ratio

2 dollars : 10 ounces

If we divide both sides by 10, then we end up with

2/10 dollars : 10/10 ounces

0.20 dollars : 1 ounce

20 cents : 1 ounce

This tells us that the unit rate for box A is 20 cents per ounce. In other words, 1 ounce costs 20 cents or each ounce costs 20 cents.

Do a similar thing for box B

3 dollars : 20 ounces

3/20 dollars : 20/20 ounces

0.15 dollars : 1 ounce

15 cents : 1 ounce

So box B costs 15 cents per ounce

In summary,

Box A's unit rate is 20 cents per ounce

Box B's unit rate is 15 cents per ounce

Box B is the better deal since it's 5 cents cheaper per ounce.

the square root of what number? if you add that, then someone will probably answer the question.