First we must find the opposite-reciprocal of the original slope.
current slope: [tex]\frac{7}{3}[/tex]
new slope: [tex]-\frac{3}{7}[/tex]
Using the new slope and the given point, we will plug them into slope-intercept form and solve for b, the y-intercept.
[tex]9 = -\frac{3}{7}(-4) + b\\\\9 = \frac{12}{7} + b\\\\-\frac{51}{7} = b[/tex]
The y-intercept is [tex]-\frac{51}{7}[/tex].
Now, we can write the formula for the new line.
Slope-intercept form: [tex]y = -\frac{3}{7}x - \frac{51}{7}[/tex]
Point-slope form: [tex]y - 9 = -\frac{3}{7}(x + 4)[/tex]