we know the workers can unpack 48 books in 2 minutes, so how many minutes for 200?
[tex]\bf \begin{array}{ccll}
books&minutes\\
\text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\
48&2\\
200&m
\end{array}\implies \cfrac{48}{200}=\cfrac{2}{m}\implies m=\cfrac{200\cdot 2}{48}
\\\\\\
m=\cfrac{25}{3}\implies m=8\frac{1}{3}\impliedby \textit{8 minutes and 20 seconds}[/tex]