Answer:
The simple subject is dollars
Explanation:
The simple subject is the noun or pronoun in the sentence that stands alone. In the sentence given, the clause, billions of tax dollars, stands as the subject of the sentence. The simple subject is the 'dollars' that was described by the other preceding descriptors.
The predicate is, spent on dollar exploration. The simple predicate is spent. The predicate is the verb that stands alone in the sentence and describes the action.
