## Intermediate Algebra: Connecting Concepts through Application

y=-$\frac{1}{3}$x+2 y+7=4(x+3)-x y=4x+12-x-7 y=3x+5 One equation has a slope of -$\frac{1}{3}$ and the other has a slope of 3. Since these numbers are opposite reciprocals of each other, the lines are perpendicular.