school assignment in enter the price and and the cost of change back.

Question

Having problems with schoolwork. In C# within Console Application
The task is to enter the price and the cost of change back.
And that it should be visible which change you want, 20, 50, or 100 notes.
For example
Price 240;
Pay 95
Switch 140; your exchange
1 100 laps
2 twenty notes
Thinking about whether to do an if stasis
Kind of like this
Anyone who knows??-.

int price;
             int pay;
             int hundred = 100;
             int fifty = 50;
             int two hundred = 200;
             int twenty = 20;
             Console.WriteLine("Enter Price");
             price = Convert.ToInt32(Console.ReadLine());
             Console.WriteLine(" paid?");
             pay = Convert.ToInt32(Console.ReadLine());
             int amount = price - pay;
             Console.WriteLine(" your gear back is " + sum);