Answer:
[tex]\begin{gathered} P=\frac{936}{42}\rightarrow\text{ (boxes of pens)} \\ B=\frac{936}{7}\rightarrow(\text{ batteries)} \end{gathered}[/tex]Explanation: Total sales in August was $936, which was sales of batteries and boxes of pens, we know that customers bought 6 times as many batteries as pens, this translates to algebra as follows:
[tex]\begin{gathered} B(\text{ \$3)+P(\$6)=\$936} \\ B=6P \\ \therefore\Rightarrow \\ 6P(\text{ \$6)+P(\$6)=\$936} \\ 36P+6P=936\rightarrow42P=936 \\ P=\frac{936}{42}\rightarrow\text{ (boxes of pens)} \\ \therefore\Rightarrow \\ B=6\times\frac{936}{42}=\frac{936}{7}\rightarrow(\text{ batteries)} \\ \\ \end{gathered}[/tex]