bearing in mind that a whole will be 5/5, so the full pan is 5/5.
[tex]\bf \begin{array}{ccll}
macaroni&pieces\\
\text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\
\frac{2}{5}&16\\\\
\frac{5}{5}&p
\end{array}\implies \cfrac{\quad\frac{2}{5} \quad }{\frac{5}{5}}=\cfrac{16}{p}\implies \cfrac{2}{5}\cdot \cfrac{5}{5}=\cfrac{16}{p}
\\\\\\
\cfrac{2}{5}=\cfrac{16}{p}\implies 2p=80\implies p=\cfrac{80}{2}\implies p=40[/tex]