#### Answer

y=$\frac{7}{3}$x+24

#### Work Step by Step

3x+7y=-21
7y=-3x-21
y=-$\frac{3}{7}$x-3
The given line has a slope of -$\frac{3}{7}$. Since the desired line is perpendicular, it must have a slope of $\frac{7}{3}$.
y-y$_1$=m(x-x$_1$)
y-3=$\frac{7}{3}$(x+9)
y=$\frac{7}{3}$x+21+3
y=$\frac{7}{3}$x+24