I have the following code which shows me the difference between two dates. now i would like to calculate my income based on that difference with a base rate of 8$ per hour but i haven't managed doing this because of the way dateTime returns me the difference. any ideeas?

```
$lastUpdate = new DateTime($lastUpdate['lastUpdate']);
$currentTime = new DateTime("2013-03-24 19:45:55");
$interval = $lastUpdate->diff($currentTime);
echo "difference " . $interval->y . " years, " . $interval->m." months, ".$interval->d." days " . $interval->h . " hours " . $interval->i . " minutes " . $interval->s . " seconds";

```