Bad operand type " * " How do I fix it? Located near bottom

[Jason Petrie]

//The purpose of this program is to simulate the shopping process by calculating the costs of the items
//and producing a receipt for the shopping trip.

//Jason Petrie 
//January 10, 2021
public class StoreReceipt {
    static final double Shirtprice = 20.00;
    static final double Mugprice = 5.00;
    static final double Hatprice = 10.00;
    String a;
    static int numbermugs;
    static int numberhats;
    static int numberShirts;
    static double ShirtTotal = Shirtprice * numberShirts;
    static double MugTotal = Mugprice * numbermugs;
    static double HatTotal = (Hatprice + 1.20) * numberhats;
    
    static double finalTotal = MugTotal + ShirtTotal + HatTotal;
    {
    }   

     private static Scanner input;

    public static void main(String[] args) {
        input = new Scanner(System.in);
        System.out.println("What's your name?");
        String a = input.nextLine();
        System.out.println("Welcome to Merchandise inc., " + a + "! We have the following items for sale:");
        System.out.println("T-shirt   $20.00   ");
        System.out.println("Hat       $10.00   ");
        System.out.println("Mug       $5.00    ");
        System.out.println("How many T-shirts do you want?");
        String numberShirts = input.nextLine();
        System.out.println("How many hats?");
        String numberhats = input.nextLine();
        System.out.println("How many mugs?");
        String numbermugs = input.nextLine();
        double tshirtTotal = Shirtprice * numberShirts;
        double chipsTotal = Hatprice * numberhats;
        double cokeTotal =  Mugprice  * numbermugs;
       
        double finalTotal = tshirtTotal  + chipsTotal  + cokeTotal;
        System.out.println("Your total is: " + finalTotal);
        
        
        System.out.println("Your total is: " + finalTotal + "Have a wodnerful day");
        
          }//end of main method
}//end of class
        

[Norm Radder]

Are you getting an error from the compiler?
What source line is the error on?

[Jason Petrie]

Its a compiler error

System.out.println("Mug       $5.00    ");
       System.out.println("How many T-shirts do you want?");
       String numberShirts = input.nextLine();
       System.out.println("How many hats?");
       String numberhats = input.nextLine();
       System.out.println("How many mugs?");
       String numbermugs = input.nextLine();
      double tshirtTotal = Shirtprice * numberShirts;
       double chipsTotal = Hatprice * numberhats;
       double cokeTotal =  Mugprice  * numbermugs;

[Carey Brown]

Jason, welcome to The Code Ranch!

When you post code please UseCodeTags (<--link). I fixed it for you this time.

[Carey Brown]

String numberShirts = input.nextLine();

"numberShirts" is of type String. You can't multiply a double by a String. You'll have to convert the String to a number first, or just use input.nextInt() to get an int instead.

[Norm Radder]

      String numberShirts = input.nextLine();
...
      double tshirtTotal = Shirtprice * numberShirts;

A String can not be used in an arithmetic expression.

[Campbell Ritchie]

Welcome to the Ranch again.

Why have you got those prices as constants in the receipt class? That looks like strange design. A receipt doesn't have a price; a product does. The object‑oriented way to do it would be to have a Product class with description and price fields. And maybe number bought.
Avoid nextLine(); if you want a number of items, the Scanner provides a method that does exactly that.
Why have you made everything static? That is usually a mistake unless you can find good justification for it; because it won't compile otherwise doesn't count as good justification.