Step-by-step explanation
- Calculate the slope with two given coordinate points by using rise over run.
![m = (y_2 - y_1)/(x_2 - x_1)](https://img.qammunity.org/2022/formulas/mathematics/college/i1pa2mybgkt3dkd7j6tklhm5t9tvmo4g5v.png)
Substitute the coordinate points value in the formula.
![m = (3 - ( - 12))/( - 9 - 6) \\ m = (3 + 12)/( - 15) \\ m = (15)/( - 15) \\ m = - 1](https://img.qammunity.org/2022/formulas/mathematics/college/rudb6ewcqo89trxo7jsv6484fa8qzqwyb3.png)
From the slope-intercept form y = mx+b where m = slope and b = y-intercept. Therefore slope = m = -1
Answer
![\large \boxed{m = - 1}](https://img.qammunity.org/2022/formulas/mathematics/college/k60fde1k3tzp2wwb9iqa5k2biwdh5sr670.png)