**escritorio:**
       b1:
          **numeros1:**
                   d1:
                     e:40
                     f:60

                   d2:
                     e:40
                     f:60
       b2:
       c2:
     (...)

mFirebaseDatabase =FirebaseDatabase.getInstance();

 String dfdf = onOptionsItemSelected();

mRef=mFirebaseDatabase.getReference("escritorio/"+dfdf+"/numeros");
    datoscarre();
}
private void datoscarre(){
    options = new FirebaseRecyclerOptions.Builder<Model>().setQuery(mRef,Model.class).build();
    firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<Model, ViewHolder>(options) {
        @Override
        protected void onBindViewHolder(@NonNull ViewHolder holder, int position, @NonNull Model model) {
            holder.setDetails(getApplicationContext(),model.getTitle(),model.getImage(),model.getLugar());
        }