Chapter 12.1, Problem 38ES

To determine

Write a regular expression to define the given set of strings. Use the shorthand notations given in the section when ever convenient. In most cases, your expression will describe other strings in addition to the given ones. but try to make your answer fit the given strings as closely as possible wïthin reasonable space limitations.

All telephone numbers that have three digits, then a hyphen, then three more digits, then a hyphen, and then four digits, where the first three digits are either $800\text{ or }888$ and the last four digits start and end with $a2$.