Your cell phone company charges $20 a month plus $0.50 per text message. Write an equation to find your total bill based on the number of text messages sent.

S = 20 + 0.5*x (S is the total bill, x is the number of text messages)

Step-by-step explanation:

The cell phone company have a fixed value you have to pay every month, independently of the number of text messages you send, and that is $20.

For each text message, you pay an additional %0.50.

So, if you send 'x' text messages in a month, you will pay the fixed $20 plus $0.5 for each text messages: you will pay 0.5 times x for the messages.

So, we can formulate the following equation:

Being "S" the total price you will pay:

S = 20 + 0.5*x