Final answer:
To better augment functions as an adverb in the sentence.
Step-by-step explanation:
In the sentence, the phrase 'to better augment' functions as an adverb. Adverbs typically modify verbs, adjectives, or other adverbs to provide information about how, when, where, or to what extent an action is performed. In this case, the phrase 'to better augment' modifies the verb 'added' by indicating the purpose or manner in which new personnel were added to the existing sales force.
Learn more about Parts of Speech