Hello Nancylynne, I'm sorry, I just saw your question. I live in a different time zone, so sometimes I can't answer right away. There isn't a rule for why we use this expression. It is just an expression, like some other expressions with "why". For example: 1. have a way with somebody (know how to deal with somebody), 2. have it your way (to tell someone that you agree to do things the way they want), 3. it cuts both ways (it has both good and bad sides), 4. go back a long way (to know someone for a long time), etc. But there is a rule for when and how to use this expression. As I said, it is an informal expression. Informal English expressions are used in everyday conversations, letters, and emails exchanged with friends, family, or people you know well. So use this expression if you are among your friends and family. If you want to write a formal letter or an essay, use the word "much". For example: She's much older than he is. (formal) She's way older than he is. (informal) So, neither one specifies a number of years, and they both mean “a lot older”. You can use either one, but in more formal settings (such as school or work), use “much older.” Have a nice day.

Way