Question

Can we say "three-year" instead of saying "three years"?

Answer 1

The phrase #1 is grammatically incorrrect because when you use the word "old" to refer to the age of a person or thing, it's a postpositive adjective. ... When you combine the words in the phrase "three years old" by hyphenating them to make it an adjective or a noun, you must use the singular noun (year).

Answer 2

yeah, in-text...