This is trivial by I'm stumped. I am trying to find the $x$-coordinate of a point on a line so that I can generate parallel diagonal lines on a graph- see image.
My slope is $m=-1$ and one point $(x_1,y_1)$ is $(1000,0)$. I would like to find the $x$-coordinate of my line at $y=100$.
I'm using the equation $y-y_1 = m(x-x_1)$ but the answer $x=900$ does not make sense to me. Where am I going off?
$100-0 = -1(x-1000)$
$100 = -x + 1000$
$x = 900$
