Answer :
[tex]unit\ rate=\frac{cost}{number\ of\ pencils}\\\\
cost=13\ dollars\\
number\ of\ pencils=5\\\\
unit \rate= \frac{13}{5}=2\frac{3}{5}\frac{dollars}{pensil}\\\\
Unit\ rate\ is\ 2\frac{3}{5}\ dollars\ per\ one\ pensil[/tex]