Answer:
Adverb
Explanation:
A prepositional phrase is a group of words that contains a preposition, its object, a noun, or pronoun used to modify the object. This kind of phrase is adjectival when it provides the description of a noun or pronoun.
Adverbial phrases modify the verbs. They tell us how, what, where, why, and to what degree, something happens. In the sentence above, the prepositional phrase, 'to install', tells us what we found difficult to do with the new program for the computer.
