Sue downloads music videos on her phone.
The cost of the video downloads (in dollars) is given by the equation c = 2v, where c is the total cost of the videos and v is the number of videos. The constant of proportionality in the equation in terms of cost per video is (1/2, 1, 2, 4) In this example, the constant of proportionality is also the (total price, unit price) of the videos.
