A rate is a little bit different than the ratio, it is a special ratio. It is a comparison of measurements that have different units, like cents and grams. A unit rate is a rate with a denominator of 1.
Per is defined as to, for, by or according to. An example of per used as a preposition is in the phrase, "as per standards," which means by the standards
Division is splitting into equal parts or groups. It is the result of "fair sharing
