What we know about the line whose equation we are trying to find out. If you need help with graphing check out this solver Graph of through the point. Use to calculate the equation of the line where represents the slope and represents the y-intercept.
A vertical line has an equation of the form x a where a is the x-intercept.
This video shows how to find the equation of a line passing through a point with a slope of zero. Pick two points on the line from the graph say 1 2 and 2 2. Intro to slope-intercept form. You may already be familiar with the ymxb form called the slope-intercept form of the equation of a line.