We are asked to create the equation that represents the cost of using a cellphone with a company that charges a fixed connection charge of $12.05 per month plus $0.06 per minute of call.
Then we set the following cost function in terms of the "x" number of minutes used for calls:
Cost(x) = 12.05 + 0.06 x
Next we are asked to find what will be the monthly cost if we use the phone for 383 minutes. So we use the function we found above, and replace x with 383 for the number of minutes of call:
Cost(x) = 12.05 + 0.06 (383) = $35.03
So the monthly cost would be $35.03 in such case.