Choose any point on each line different from (0,0) to find the constant of proportionality.
Notice that, for example, in the first graph, the point (4,4) lies in the line.
Divide the y-coordinate over the x-coordinate to find the constant of proportionality. This method is only valid when the point (0,0) is in the line.
For the first graph, the constant of proportionality is:
Which is equal to 1.
For the second graph, notice that the point (8,4) is in the line. Again, divide the y-coordinate over the x-coordinate to find the constant of proportionality:
Which is equal to 1/2.
For the third graph:
Notice that the point (4,8) is in the line of the third graph.
By dividing 8/4, we notice that the constant of proportionality is equal to 2.