title: Get order subtotal value in WooCommerce
body: <p>I use the module for calculating delivery by local carrier, but the module don't calculate shipping costs to the total.<br>
  In the <code>wp-content/plugins/woocommerce/templates/order/order-details.php</code> I added the following code to take the amount of shipping and subtotal:</p>
  
  <pre><code>     &lt;?php $a = array(
           get_post_meta($order_id, 'Order_subtotal', true),
           get_post_meta($order_id, 'Econt_Customer_Shipping_Cost', true));
       ?&gt;
       &lt;tr class="total-cost"&gt;
           &lt;th&gt;&lt;?php _e( 'Total:', 'woocommerce'); ?&gt;&lt;/th&gt;
           &lt;td&gt;&lt;?php echo array_sum($a); ?&gt; &lt;?php echo get_woocommerce_currency_symbol(); ?&gt;&lt;/td&gt;
       &lt;/tr&gt;
  </code></pre>
  
  <p>As a result, I get only the value of <code>"Econt_Customer_Shipping_Cost"</code>, but not from <code>"Order_subtotal"</code> to get the total.</p>
  
  <p>Please, can someone tell me what to use to get a working subtotal?</p>