Add x days to a current date

To add 3 days to current date, here is the way:
In before add event:
$values["date_scheduled"] = NOW();

$date_scheduled = $values["date_scheduled"];
$newdate = strtotime ( '+3 day' , strtotime ( $date_scheduled ) ) ;

$newdate = date ( 'Y-m-j' , $newdate );
$values["date_expired"] = $newdate;
return true;