E varies directly with W:
[tex]E=k*W[/tex]Use the given data to find the value of the constant k:
[tex]\begin{gathered} 2=k*18 \\ k=\frac{2}{18} \\ \\ k=\frac{1}{9} \end{gathered}[/tex]Equation of the relationship:
[tex]E=\frac{1}{9}W[/tex]Use the equation above to find E when W=13:
[tex]\begin{gathered} E=\frac{1}{9}(13) \\ \\ E=\frac{13}{9} \end{gathered}[/tex]Then, E is 13/9, when W=13
