The formula used to calculate the slope of a line is given to be:
![m=(y_2-y_1)/(x_2-x_1)](https://img.qammunity.org/2023/formulas/mathematics/high-school/78uaqhwt0aws3qfwxigaftpihnmb1gzxtp.png)
The points that the line passes through are:
![\begin{gathered} (x_1,y_1)=(4,9) \\ (x_2,y_2)=(22,3) \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/tjgxmc36j0nbaeq1a9hvqsu8c3wo0mq00f.png)
Therefore, the slope of the line is given to be:
![\begin{gathered} m=(3-9)/(22-4)=(-6)/(18) \\ m=-(1)/(3) \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/y545ur8z1qv9za9ldy1tt7bg6yubrk6gpt.png)
Recall that the slopes of parallel lines are equal.
Therefore, the slope of the parallel line is -1/3.