## Elementary Geometry for College Students (6th Edition)

$\frac{-b}{a}$
As we know that the slopes of the parallel lines are equal. Slope of the line containing (a,0) and (0,b) m = $\frac{y2-y1}{x2-x1}$ = $\frac{b-0}{0-a}$ =$\frac{-b}{a}$ Therefore the slope of the line that is parallel to the line joining(a,0) and(0,b) is $\frac{-b}{a}$