Java

import java.util.Scanner;

public class Orders {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String command = sc.nextLine();
        LinkedHashMap <String, List<Double>> products = new LinkedHashMap<>();

        while(!"buy".equalsIgnoreCase(command)){
            String[] tokens = command.split("\\s+");
            String name = tokens[0];
            double price = Double.parseDouble(tokens[1]);
            double quantity = Double.parseDouble(tokens[2]);

            List <Double> list = new ArrayList<>();
            list.add(0, price);
            list.add(1, quantity);

            if(!products.containsKey(name)){
                products.put(name, list);
            } else {
            List <Double> list2 = new ArrayList<>();
            list2.add(0, price);
            list2.add(1, quantity + products.get(name).get(1));
                products.put(name, list2);
            }

            command = sc.nextLine();
        }

        products.entrySet().
                forEach(e-> System.out.printf("%s -> %.2f%n", e.getKey(), e.getValue().get(0) * e.getValue().get(1)));

    }
}