Add text before regular price only In Woocommerce

gistfile1.txt

function bd_rrp_price_html( $price, $product ) {
 
  $retun_string = 'RRP: ' . $price;
  return $return_string;
 
}
add_filter( 'woocommerce_get_price_html', 'bd_rrp_price_html', 100, 2 );