Question

What is the slope of a line that is perpendicular to (3,9) and (7, 15)?

Answer 1

Your line between `(3,9)` and `(7,15)` has slope `m` given as:
`m=(Deltay)/(Deltax)=(15-9)/(7-3)=6/4=3/2`
The line perpendicular to this line will have slope `m_1` equal to:
`m_1=-1/m=-2/3`