The constant of proportionality is k = 5
For direct proportion equations, you divide the y value over its corresponding x value to get the value of k.
For example, the point (x,y) = (2,10) is on the diagonal line. So k = y/x = 10/2 = 5.
Another example: the point (x,y) = (6, 30) is also on the same diagonal line, so k = y/x = 30/6 = 5 is the same result as before.
You can use any point on the diagonal line as long as it is not (0,0). This is because division by zero is not allowed.
side note: the direct proportion equation y = k*x becomes y = 5*x which is the graph of that diagonal line. The slope is m = 5, the y intercept is b = 0. All direct proportion graphs go through the origin as shown in the diagram.
