Given data:
The credit that remains after 24 minutes is $21.64.
The credit that remains after 55 minutes is $17.30.
The expression for the equation is,
[tex]\begin{gathered} y-21.64=(\frac{17.30-21.64}{55-24}(x-24) \\ y-21.64=-0.14x+3.36 \\ y=-0.14x+25 \end{gathered}[/tex]Substitute 79 for x in the above expression.
[tex]\begin{gathered} y=-0.14(79)+25 \\ =13.94 \end{gathered}[/tex]Thus, the credit that remains after 79 minutes is $13.94.
