#### Answer

a) You would have to send/receive 100 text messages in order for the plans to cost the same each month.
b) The first plan is the best choice.

#### Work Step by Step

Create two equations to represent the cost of each plan per month. x will represent the amount of text messages sent/received each month.
Plan One: 40 + .20x
Plan Two: 60
Now that you have both equations, set them equal to each other to find out how many send/receive messages are needed in order for the cost of both plans to be the same.
40 +.20x = 60
.20x=20
x=100.
Now that we have found our x-value, we now know that it will take 100 messages for both of the prices of the plans each month to be the same.
In the second part, we are asked to determine which plan is the cheapest if you only receive/send and average of 50 text messages per month. Because 50 is less than 100, plan one is cheaper.