What is 90 of 80?

The term "90 of 80" does not have a specific meaning and is not a commonly used phrase or expression. As such, it is difficult to provide information without additional context or clarification. It is possible that "90 of 80" could be a mathematical equation, but without knowing the intended interpretation, it is uncertain how to proceed.

If you can provide more details or rephrase the question, I would be happy to help you with the information you are looking for.