Question 1000789
You want the equation either in standard form or in slope intercept form.  Put into the form which you have the most comfort.


{{{y=(1/7)x-14/7}}}

{{{y=(1/7)x-2}}}

The slope plainly is  {{{1/7}}}.  The slope for any line perpendicular will be  the negative reciprocal, in this case,  {{{highlight_green(-7)}}}.


You can still stay with slope-intercept form, now wanting the equation {{{highlight_green(y=-7x+b)}}} perpendicular to  {{{y=(1/7)x-2}}}.


Solve for b, and substitute the point which needs to be on the line, and then finish the equation.
{{{b=y+7x}}}
{{{b=-3+7*8}}}
{{{highlight_green(b=53)}}}


Put together...