If you look carefully at the graph, you may see that the slope of the line is 3-4 -1 ---------------- = ------ = m 7-4 3
thus, you have the slope of the line and two points on the line. Suppose we choose the point (4,4) and subst. the known slope and the coordinates of this point into the point-slope formula for the eqn of a str line:
y-y1 = m (x-x1)
y-4 = (-1/3)(x-4)
This is the desired equation. You could, if you wished, change this into slope-intercept form.
