Opencart 2.3 display discount percentage?

Question

WordPress

I'm trying to display what percentage of the discount in the product CARD
added to the controller (highlighted what I added)

if ((float)$product_info['special']) {


        $data['special'] = $this->currency->format($this->tax->calculate($product_info['special'], $product_info['tax_class_id'], $this->config->get('config_tax')), $this->session->data['currency']);

        $data['discount_amount'] = $this->currency->format($this->tax->calculate(($product_info['price'] - $product_info['special']), $product_info['tax_class_id'], $this->config->get('config_tax')), $this->session->data['currency']);	

// Сюда вставил     $data['skidka'] = round(100-($product_info['special']/($product_info['price']/100)));</b>



      } else {
        $data['special'] = false;
// Сюда вставил        $data['skidka'] = false;


      }



$data['products'][] = array(
          'product_id'  => $result['product_id'],

          'thumb'       => $image,
          'name'        => $result['name'],
          'description' => utf8_substr(strip_tags(html_entity_decode($result['description'], ENT_QUOTES, 'UTF-8')), 0, $this->config->get($this->config->get('config_theme') . '_product_description_length')) . '..',
          'price'       => $price,
          'special'     => $special,
// Сюда вставил         'skidka' 	  =>    $skidka,
          'tax'         => $tax,
          'sku'         => (empty($result['sku'])) ? '' : $this->language->get('text_sku') .' '. $result['sku'],
          'minimum'     => $result['minimum'] > 0 ? $result['minimum'] : 1,
          'rating'      => $rating,
          'href'        => $this->url->link('product/product', 'product_id=' . $result['product_id'])
        );
      }

I display in the card template Works if there is a discount if the discount is not assigned, errors appear on this line 'skidka' => $skidka, Notice: Undefined variable: skidka in /***********/catalog/controller/ product/product.php on line 478Notice can anyone know why false does not work?
<span>- <?php echo $skidka; ?>%</span>