Question 949478
Here is shown two things but not the answers to your questions.


If the slopes of each of two lines in a plane are m and M, and if the {{{m*M=-1}}}, then the two lines are perpendicular.  In other words, if the slopes are negative reciprocals of each other, then the lines are perpendicular.


Slope-Intercept form equation for a line is often represented y=mx+b.
The variable m is the slope.


A standard form equation of a line as Ax+By=C, can be solved for y in terms of x.
{{{By=-Ax+C}}}
{{{y=-Ax/B+C/B}}}
{{{y=-(A/B)x+C/B}}}
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This shows you that the slope of {{{Ax+By=C}}}  would be {{{-A/B}}}.  A line perpendicular to it would have a slope {{{B/A}}}.