We need to find the price of 1 bottle. From the graph, 2 bottles cost $1. If x represents the cost of 1 bottle, the next proportion must be satisfied:
[tex]\frac{1\text{ \$}}{2\text{ bottles}}=\frac{x\text{ \$}}{1\text{ bottle}}[/tex]
Solving for x:
[tex]\begin{gathered} 1\cdot1=x\cdot2 \\ \frac{1}{2}=x \\ 0.5\text{ \$}=x \end{gathered}[/tex]
