The following graph shows a relationship between the size of the household and the average amount of time, in hours, each member of the household spends on chores per week.

To determine the equation of the line in this case, you need to choose two points of the graph.
 Let
 Point 1
 P1 = (x1, y1)
 Point 2
 P2 = (x2, y2)
 The slope of the line is
 m = (y2-y1) / (x2-x1)
 The equation of the line (choosing any point) will be
 y-y1 = m (x-x1)
 For this particular case, the line that best represents the graph is:
 y = -0.35x + 5.3