Hello Aspara Gus, I, too, wanted to ask a question or two on how we describe how old somebody is, please. 

Could we write any of these, for example, when describing what somebody's age is?

- He's 30. 
- He's 30 years old. 
- He's 30 year old.
- He's 30-year-old. 
- His age is 30. 
- He is at the age of 30 (now). 

TomJCould we write any of these, for example, when describing what somebody's age is?

He's 30. Good.
He's 30 years old. Good.
He's 30 year old. Wrong. But you can say He’s one year old.
He's 30-year-old. Wrong.
His age is 30. Not wrong, but unusual.
He is at the age of 30 (now). Not wrong, bu