Accepted Answer
Answer: The subordinate clause in the sentence is "which was to be delivered in unmarked five dollar bills." and it is used as an adjective clause.Explanation: Like any clause that begins with a relative pronoun ("which" in this case), it cannot stand as a sentence on its own; it depends on the noun "ten thousand dollars" because it acts as a modifier of it. This function of modifying a noun applies only to adjectives, so this is an adjective clause.
Suggested Answer
"which was to be delivered in unmarked five dollar bills" is the subordinate sentence, since "the note repeated the telephone..." is the main one.