Answer:
y = -3x + 12
Explanation:
The equation of a line with slope m that passes through the point (x1, y1) can be calculated as:
[tex]y-y_1=m(x-x_1)[/tex]So, replacing m by -3, and (x1, y1) by (1, 9), we get:
[tex]y-9=-3(x-1)[/tex]Finally, solving for y, we get:
[tex]\begin{gathered} y-9=-3x-3(-1) \\ y-9=-3x+3 \\ y-9+9=-3x+3+9 \\ y=-3x+12 \end{gathered}[/tex]Therefore, the answer is:
y = -3x + 12
