Customizing total_paid in an e-mail template.

[mesiiiny]

Hello, 
 
Need help with adjusting display prices in the email template. 
I need to email me the template did not show price orders but only 30% of the order price. 
 
I want to define the file validation.php module add_pay_invoice. 
 
The entry looks like this:

$mailVars = array(

'{splatnost}' => Configuration::get('PAY_INVOICE_DAYS'),

 

'{total_to_pay}' => '{total_paid} ',      // in this line need to count 30% of the value total_paid !!!!

 

'{splatnost_den}' => date("d.m.Y",strtotime('+'.Configuration::get('PAY_INVOICE_DAYS').' days'))

);

 

 

Should look like the correct entry that I run only 30% of the value total_paid?