Question 704269
Use x for how many videos rented,
y for the amount of money each store separately receives,


Customer Costs_________A________________B
membership___________$15________________0
vid. rent rate_______2x_________________3.50x
Function sum______y=2x+15______________y=3.5x


Looking for at how many videos rented are sales the same, when are "y" of each equal?  2x+15=3.5x, find x.  Solve that and find x=10, so each store A and B bring in the same amount of cash when each rents 10 videos.


{{{graph(350,350,-10,40,-10,60,2*x+15,3.5*x)}}}


This can really be an example in which the number of members is also a variable, so the "y=..." should really be a function of two variables, not just one variable.