What is the subject of the sentence?

Four hundred pages (seems, seem) like an awfully long reading assignment for the holiday weekend.]]> Is the subject sentence singular or plural?

Four hundred pages (seems, seem) like an awfully long reading assignment for the holiday weekend.]]> Four hundred pages seems like an awfully long reading assignment for the holiday weekend. Type the correct form of the words in parentheses into the box, then submit it and say the sentence.

Four hundred pages (seems, seem) like an awfully long reading assignment for the holiday weekend.]]>