Question 51·Hard·Linear Equations in Two Variables

A courier company charges customers according to the linear model

where $C$ is the total cost (in dollars) for a delivery of $m$ miles, $p$ is a fixed pickup fee (in dollars), and $k$ is the cost per mile (in dollars).

• A $3$-mile delivery costs $13.50.
• An $8$-mile delivery costs $26.00.

What is the value of $p$, the fixed pickup fee, in dollars?