5. [9.5.1] Two of your students, Nancy and Barbara, are working together to describe how the sequence of figures seen below grows. Nancy says to get from one shape to the next, you need to add two squares to the tops of the figures and then count. Barbara wants to use n for any figure in the sequence and relate the number of squares to the position of the nth shape in the sequence. Who is using explicit reasoning? How do you know? [10 points] 6th