Answer :
[tex]\begin{gathered} store\text{ 1}\Rightarrow3\times12=10.49\text{ \$} \\ 1\text{bottle is}\Rightarrow0.29\text{ \$} \\ \text{Store 2}\Rightarrow1\times12=3.89\text{ \$} \\ 1\text{ bottle is}\Rightarrow0.324\text{ \$} \\ \text{Store 3}\Rightarrow4\times6=7.99\text{ \$} \\ 1\text{ bottle is}\Rightarrow0.33 \\ \text{Store 4}\Rightarrow1\times6=2.29\text{ \$} \\ 1\text{ bottle is}\Rightarrow0.38\text{ \$} \\ Store\text{ 1 is the answer} \end{gathered}[/tex]