What is the equation of the line described below written in slope-intercept form? the line passing through point the origin, parallel to the line whose equation is y = -2x + 5 y = -2x y = -x y = x y = 2x

The general equation for slope-intercept form is y = mx + b, where m = the slope of the equation, b = the y intercept, and x and y are your variables (and the coordinate points on the graph). 
Remember that for parallel lines, the slope, m, is the same for both equations. The equation you're given, y = -2x + 5, is already in slope-intercept form and the -2 in front of x is m, your slope. That means all parallel equations have m = -2. The value of b can be anything you want (other than 5 because that would make the equation the same line as the one you already have).

If you look at your choices, all of them pass through the origin (0, 0) because you'll get y = 0 if you plug in x = 0. That means you're looking for an equation with a slope m = -2, making it parallel. The only equation with that slope is
A) y = -2x