Determine the number of gallons in a peck.
[tex]\begin{gathered} 1\text{ peck = }\frac{1}{4}\text{ bushel} \\ 1\text{ peck = }\frac{1}{4}\cdot8\text{ gallons} \\ 1\text{ peck = 2 gallons} \end{gathered}[/tex]The price per pack is $20 or price of 2 gallons is $20.
Determine the price of 1 gallon.
[tex]\frac{20}{2}=10[/tex]So cost per gallon is $10.