where m is the slope of the line and b is the y-intercept of the line, or the y-coordinate of the point at which the line crosses the y-axis. To write an equation in slope-intercept form, given a graph of that equation, pick two points on the line and use them to find the slope.
The equation is y = -3/4x + 4. Because the y-intercept found here is 4, and to get to another point on the line you need to go down on the y-axis 3, -3, and go over to the right of the graph on the x-axis 4.
