5. By counting the triangles she could see for any length, Jenna says she figured out a patt- for the number of rods. For overall length 7, she sees 7 triangles and 6 rods connecting
these triangles, so she writes 7 x 3 + 6 = 27. For length L, she writes N = 3L + L - 1.
Explain where she gets the 3L and the L. - 1 in her expression.