To determine the expression that represents Roxy's cell phone bill for last month, we need to account for two components: the fixed monthly charge for unlimited calling and the variable charge for the text messages sent.
1. Monthly Charge for Unlimited Calling:
Roxy has a fixed monthly charge of \[tex]$40 for unlimited calling. This constant amount does not change regardless of the number of text messages she sends.
2. Charge per Text Message:
In addition to the monthly calling charge, the cell phone company also charges \$[/tex]0.20 for each text message sent. Let [tex]\( t \)[/tex] represent the number of text messages Roxy sent last month.
3. Total Text Message Cost:
The cost for the text messages can be calculated by multiplying the number of text messages ([tex]\( t \)[/tex]) by the charge per message (\$0.20). This gives us the expression [tex]\( 0.20t \)[/tex].
4. Total Cost Calculation:
To find the total cost of Roxy's bill last month, we need to add the cost of the text messages to the monthly charge for unlimited calling. Therefore, the expression representing the total cost [tex]\( C \)[/tex] is:
[tex]\[
C = \text{Monthly Charge} + \text{Text Message Cost}
\][/tex]
Substituting the appropriate values, we get:
[tex]\[
C = 40 + 0.20t
\][/tex]
Thus, the expression that represents the cost of Roxy's bill last month before any taxes or additional fees is:
[tex]\[
\boxed{40 + 0.2t}
\][/tex]
