EXERCISE P7–4The hyphen
Example:

Gail Sheehy writes that at age twenty five many people assume that the choices they make are irrevocable.

Gail Sheehy writes that at age twenty-five many people assume that the choices they make are irrevocable.

Numbers under one hundred expressed as two words are hyphenated.

For more help, see sections P7-d to P7-i.