Answer
$ y-2=2(x-4) \qquad$ ... point-slope form
$ y=2x-6 \qquad$ ... slope-intercept form
Work Step by Step
If two nonvertical lines are parallel, then they have the same slope.
The given blue line,$\ y=2x$, has slope $m=2.$
So, the line L has slope $m=2$, and passes through $(x_{1},y_{1})=(4,2)$
We write the point-slope equation:
$y-y_{1}=m(x-x_{1})$
$ y-2=2(x-4) \qquad$ ... point-slope form
Simplify to slope-intercept form (solve for y)
$ y-2=2x-8 \qquad$ ...add $2$
$ y=2x-6 \qquad$ ... is the slope-intercept form
