How to return the isolated result of a multiplication expression from a CodeIgniter query

I am trying to retrieve data from a database by using multiple where when I call on Views of data actually appears letters array? What is wrong?

Models

function produk()
{
    $sql = "
        SELECT penjualan * jumlah
        FROM toko           
        WHERE toko = 'ALFA' AND produk = 'susu'
    ";
    
    return $this->db->query($sql)->result();
}

Controllers

public function index()
{
    $data = array(
        'produk' => $this->m_ff->produk(),
        'isi' => 'home/v_ff'
    );
    $this->load->view('layout/wrapper', $data);
}

Views

<?php echo produk; ?>

make sure you column name are correct

Need to change your query to

  SELECT * FROM toko             
            WHERE toko = 'ALFA' AND produk = 'susu'

If you want to multiply two colunm Using Active record then use it as

 $this->db->select("`penjualan`*`jumlah` as multiply", FAlSE);// for multiplication of two column
   $this->db->where("toko","ALFA");
   $this->db->where("produk","susu");
   $query=$this->db->get('toko');
   $ret = $query->row();// for single row
   return $ret->multiply;

And in View you get your data as

<?php echo $produk); ?>