Use the image to answer the question.
An illustration shows a graph labeled Football Cost. The horizontal axis is labeled Quantity and ranges from 0 to 5 in increments of 1. The vertical axis is labeled Cost and ranges from 0 to 39 in increments of 3. An upward slanting line segment connects points plotted at left parenthesis 0 comma 0 right parenthesis, left parenthesis 1 comma 9 right parenthesis, left parenthesis 2 comma 18 right parenthesis, left parenthesis 3 comma 27 right parenthesis, and left parenthesis 4 comma 36 right parenthesis.
The price for footballs is displayed in the graph. Derive the equation of the proportional relationship through the origin.
(1 point)
The equation of the proportional relationship through the origin can be derived by finding the slope of the line segment connecting the points (0,0) and (4,36).
To find the slope, we use the formula: slope = (y2 - y1) / (x2 - x1)
Using the given points, (x1,y1) = (0,0) and (x2,y2) = (4,36), we can plug them into the slope formula:
slope = (36 - 0) / (4 - 0) = 36 / 4 = 9
Therefore, the equation of the proportional relationship through the origin is: Cost = 9 * Quantity