# How do you find the slope that is perpendicular to the line 3x+9y=9?

The slope of the perpendicular line is ${m}_{1} = 3$
The slope of the line $3 x + 9 y = 9 \mathmr{and} 9 y = - 3 x + 9 \mathmr{and} y = - \frac{1}{3} x + 1$ is $m = - \frac{1}{3}$(comparing with the equation $y = m x + c$).We know the product of slopes of prpendicular lines is $- 1 \therefore {m}_{1} = - \frac{1}{- \frac{1}{3}} = 3$[Ans]