Declare variables for each of the following and initialize them to the value
in parenthesis:

1. Price of a shirt ($15.99)

	 double shirt_price = 15.99;

2. Number of shirts in stock (100)

	 int num_shirts = 100;

3. Sales tax rate ($0.0775)

	 double sales_tax_rate = 0.0775;

4. Number of customers in database (do not initialize)

	 int num_customers;

5. Street address of store (do not initialize)

	 string store_address;