Explanation:

• The following code is used to show the formatted retail price of items, when the item is in 15% mark-up.
• In this program the value 0.15 is multiplied by whole sale price to get the 15% of the whole sale price.
• If 15 percentage of whole sale price is added with the whole sale price then the Retail price will be display.
• The method string.Format("{0:0.00}",variableNmae) is used to format the decimal number up to two decimal places.
   

Program:

// Create a class named FormatedRetailPrice
class FormatedRetailPrice
{
	// Create a main method to run the program
	static void Main(string[] args)
	{
		// Declare a string variable named itemName to store the item name
		string itemName = "Ruggy Shoes";
		// Declare a double variable named wholeSalePrice to store the whole sale price.
		double wholeSalePrice = 52.00;			

		// Display item name
		Console.WriteLine("Item: " + itemName);
		// Display whole sale price
		Console.WriteLine("Whole Sale Price: " + string.Format("{0:0.00}", wholeSalePrice));
		// Display retail price.
		Console.WriteLine("RetailPrice: " + string.Format("{0:0.00}", (wholeSalePrice + (wholeSalePrice * 0.15)))); 

		// The following lines of code is used to reassign the
		// memory location vlaues for a Teno Jacket.
		itemName = "Teno Jacket";
		wholeSalePrice = 71.50;

		Console.WriteLine();
		// Display item name
		Console.WriteLine("Item: " + itemName);
		// Display whole sale price
		Console.WriteLine("Whole Sale Price: " + string.Format("{0:0.00}", wholeSalePrice));
		// Display retail price.
		Console.WriteLine("RetailPrice: " + string.Format("{0:0.00}", (wholeSalePrice + (wholeSalePrice * 0.15))));

		Console.ReadKey();
	}
}

Output:

Item: Ruggy Shoes
Whole Sale Price: 52.00
RetailPrice: 59.80

Item: Teno Jacket
Whole Sale Price: 71.50
RetailPrice: 82.23