Sandwich Class Static Variable

Sandwich class. I have thus far completed creating a sandwich class with a seperate sandwich Tester class to run with it. (this is according to the assignment). Now I must create Static variables for the sandwich class:

Add two static variables to the Sandwich class to count how many sandwiches are sold and how many slices of tomato are used. Initialize each to 0.Where do you add code to increment the sandwich counter? Determine this and then add code.

public class Sandwich
{
static int numOfSold = 0;
static int slicesUsed = 0;
private String meat;
private int numOfSlicesOfTomato;
private boolean lettuce;

[code]....