A wireless carrier offers the following plans that a person is considering.

The Family Plan: $90 monthly fee, unlimited talk and text on up to 8 lines, and data charges of $40 for each device.

The Mobile Share Plan: $120 monthly fee for up to 10 devices, unlimited talk and text for all the lines, and data charges of $35 for each device.

Use P for the number of devices that need data plans as part of their cost.



Find the model of the total cost of the Family Plan.
Find the model of the total cost of the Mobile Share Plan.
Assuming they stay under their data limit, find the number of devices that would make the two plans equal in cost.
If a family has 3 smart phones, which plan is more affordable?