Java program

 // Define the Product class

class Product {

    private String name;

    private double price;

    private int quantity;

    private double taxRate; // Tax rate as a decimal (e.g., 0.08 for 8%)

    // Constructor to initialize the product

    public Product(String name, double price, int quantity, double taxRate) {

        this.name = name;

        this.price = price;

        this.quantity = quantity;

        this.taxRate = taxRate;

    }

    // Method to calculate the total cost including tax

    public double calculateTotalCost() {

        double subtotal = price * quantity;

        double taxAmount = subtotal * taxRate;

        double totalCost = subtotal + taxAmount;

        return totalCost;

    }

    // Getters and setters (optional based on requirements)

    public String getName() {

        return name;

    }

    public void setName(String name) {

        this.name = name;

    }

    public double getPrice() {

        return price;

    }

    public void setPrice(double price) {

        this.price = price;

    }

    public int getQuantity() {

        return quantity;

    }

    public void setQuantity(int quantity) {

        this.quantity = quantity;

    }

    public double getTaxRate() {

        return taxRate;

    }

    public void setTaxRate(double taxRate) {

        this.taxRate = taxRate;

    }

}

// Main class to demonstrate the product calculation

public class ProductCalculation {

    public static void main(String[] args) {

        // Create a product instance

        Product product = new Product("Smartphone", 999.99, 2, 0.08); // Example values: price, quantity, tax rate

        // Calculate the total cost including tax

        double totalCost = product.calculateTotalCost();

        // Display the result

        System.out.println("Product: " + product.getName());

        System.out.println("Price per unit: $" + product.getPrice());

        System.out.println("Quantity: " + product.getQuantity());

        System.out.println("Tax rate: " + (product.getTaxRate() * 100) + "%");

        System.out.println("Total cost (including tax): $" + totalCost);

    }

}

public class BookPriceCalculator {

    public static void main(String[] args) {

        String productName = "Book";

        int quantity = 5;

        double taxRate = 0.1; // Assuming tax rate is 10%

        double originalPrice = 20.0; // Assuming original price of each book is $20

        // Calculate tax amount

        double taxAmount = originalPrice * taxRate;

        // Calculate total price including tax

        double totalPrice = (originalPrice + taxAmount) * quantity;

        // Print out the details

        System.out.println("Product name: " + productName);

        System.out.println("Quantity: " + quantity);

        System.out.println("Original Price per book: $" + originalPrice);

        System.out.println("Tax Rate: " + (taxRate * 100) + "%");

        System.out.println("Tax Amount per book: $" + taxAmount);

        System.out.println("Total Price including tax: $" + totalPrice);

    }

}