public class Buku {
    public String judul;
    String kodeInternal;
    private double hargaBeli;

    public Buku(String judul, String kodeInternal, double hargaBeli) {
        this.judul = judul;
        this.kodeInternal = kodeInternal;
        this.hargaBeli = hargaBeli;
    }

    public double hargaJual() {
        return hargaBeli * 1.3;
    }

    String labelInternal() {
        return kodeInternal + " (internal)";
    }
}