Question 1176722:  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 for  
up to 2 GB of data per 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 up to a shared total of 10 GB of data. 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 
 Answer by CPhill(1987)      (Show Source): 
You can  put this solution on YOUR website! Let's break down the cost of the Family Plan and create a model.
 
**Understanding the Family Plan**
 
* **Monthly Fee:** $90 (fixed cost) 
* **Unlimited Talk and Text:** Included for up to 8 lines 
* **Data Charges:** $40 per device (up to 2 GB per device) 
* **Number of Devices with Data:** P
 
**Building the Cost Model**
 
1.  **Fixed Cost:** The $90 monthly fee is a constant, regardless of the number of devices.
 
2.  **Variable Cost:** The data charge is $40 per device, and we have P devices. So, the data cost is $40 * P.
 
3.  **Total Cost:** To find the total cost, we add the fixed cost and the variable cost.
 
**The Model**
 
The total cost (C) of the Family Plan can be represented by the following equation:
 
* **C = 90 + 40P**
 
Where:
 
* C = total monthly cost 
* P = number of devices with data plans 
 
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