The constant of proportionality is 5
For the first bar day: 1 cell phone sold: 5 (unit rate:5)
second bar day: 2 cell phones sold: 10 (unit rate:5)
third bar Day: 3 cell phones sold: 15 (unit rate: 5)
fourth bar day: 4 cell phones sold: 20 (unit rate 5)
Basically you divide the cell phones sold by the day or [tex]\frac{rise}{run}[/tex]
Hope this helped <3
