Problems 69–78. The purpose of these problems is to keep the material fresh in your mind so that you are better prepared for later sections, a final exam, or subsequent courses such as calculus.

The normal line to a graph at a point is the line perpendicular to the tangent line of the graph at the point. If the tangent line is y = 2/3x − 1 when f (3) = 1, find an equation of the normal line.