The answer to this is D, $990.00
They will make the same amount after 10 phones sold. Before that Plan A is the better plan. After 10, Plan B is the better plan.
You can find the point of intersection by modelling the two equations and setting them equal to each other. If x is equal to phones sold:
250 + 25x = 50x
250 = 25x
10 = x
Therefore, you make the same at 10 phones.
480 is 100%
48 = 10%
480 = 100%
