Question: I need help with my project for school. I have been working on it and finally figured out how to output the beginning odometer and ending odometer = total miles driven. For total cost, I need it to add $15 per day rented, plus $0.12 per mile. How would I do this? Here is the code I have now: 

```
//Step 1: Declaring variables to store our information.
decimal beginningOdometerDecimal;
decimal endingOdometerDecimal;
decimal rentedDecimal;
decimal totalSaleDecimal;
decimal averageSalesDecimal;
decimal carsReturned;
decimal totalMilesDecimal;
decimal finalCostDecimal;

//Step 2: Get the information from the user.
beginningOdometerDecimal = Decimal.Parse(txtBegin.Text);
endingOdometerDecimal = Decimal.Parse(txtEnd.Text);
rentedDecimal = Decimal.Parse(txtRent.Text);

//Step 3: Mathmatematical Calculations.
totalMilesDecimal = endingOdometerDecimal - beginningOdometerDecimal;
finalCostDecimal = totalMilesDecimal * (Decimal)0.12 + rentedDecimal + 15;

```

As you see, I used finalCostDecimal is equal to totalmilesdecimal \* $0.12 + rentedDecimal + 15. I don't think I used the right code. Can anyone please help me here? I am stuck and have tried a lot. Thanks!

Answer: 
If `rentedDecimal` is the number of days the car was rented, then your calculation should be:

```
 finalCostDecimal = (totalMilesDecimal * 0.12m) + (rentedDecimal * 15.0m);

```
$15 per day rented plus $0.12 per mile

($15 per day rented) plus ($0.12 per mile)

($15 \* days rented) + ($0.12 \* miles driven)

```
finalCostDecimal = (15 * rentedDecimal) + (0.12 * totalMilesDecimal)

```