Question 1025577
The slope of a line  with equation {{{y=mx+b}}} is {{{m}}} ,
so the slope of a line  with equation {{{y=(-1/2)x-3}}} is {{{-1/2}} .
If two lines sre perpendicular, the product of their slopes is {{{-1}}} ,
so for a line perpendicular to slope of a line  with equation {{{y=mx+b}}} , {{{(-1/2)m=-1}}} ---> {{{m=2}}} .
A line with slope {{{m}}}  passing through point {{{P(x[P],y[P])}}}
has the equation {{{y=y[P]=m(x=x[P])}}} (in point-slope form),
so the line  passing through (10,10) and perpendicular to the line described by {{{y=(-1/2)x-3}}}
has the equation
{{{highlight(y-10=2(x-10))}}} <---> {{{highlight(y=2x-10)}}}