from the question
24-pack of Diet coke cost $9.
let x be the cost of a diet coke
therefore,
[tex]\begin{gathered} 24x\text{ = \$9} \\ \text{divide both side by 24} \\ x\text{ = }\frac{\text{\$9}}{24} \\ x\text{ = \$0.38 ( 2 decimal place)} \end{gathered}[/tex]Therefore the cost of a pack of diet coke is $0.38
Also
12-pack of their generic Big K Diet Cola cost $2.75.
let y be the cost of a pack of generic Big Diet Cola
therefore
[tex]\begin{gathered} 12y\text{ = \$2.75} \\ divide\text{ both side by 12} \\ y\text{ = }\frac{\text{\$2.75}}{12} \\ y\text{ = \$0.23 ( 2 decimal place)} \end{gathered}[/tex]Therefore, the cost of a pack of generic Big K Diet Cola is $0.23
calculating the difference in price
[tex]\begin{gathered} Difference\text{ in price = x - y} \\ \text{Difference in price = \$0.38 - \$0.23} \\ \text{Difference in price = \$0.15} \end{gathered}[/tex]This means that the difference between the price of Diet Coke and generic Big K Diet Cola is $0.15
Therefore
The name-brand is $0.15 more expensive than generic soda