How can I sum multiple time in laravel 5.2

You can figure out the different using Carbon. Need some little trick to add these times. You can do it this way:

$a = '09:00:00';
$b = '08:00:00';
$c = '09:00:00';

//convert the $a in carbon instance. 
//convert $b and $c in integer, you can add only integer with carbon. 
$d = Carbon::createFromFormat('H:i:s',$a)->addHours(intval($b))->addHours((intval($c)));

//convert the time "45:00:00" to carbon
$e = Carbon::createFromFormat('H:i:s','45:00:00');

//return the difference
$e->diffInHours($d)

You can do the following:

  $sumSeconds = 0;
  foreach($times as $time) {
      $explodedTime = explode(':', $time);
       $seconds = $explodedTime[0]*3600+$explodedTime[1]*60+$explodedTime[2];
       $sumSeconds += $explodedTime;
  }
  $hours = floor($sumSeconds/3600);
  $minutes = floor(($sumSeconds % 3600)/60);
  $seconds = (($sumSeconds%3600)%60);
  $sumTime = $hours.':'.$minutes.':'.$seconds;

This is the code for suming the three times (supposed that they are in array) and the code for subtracting will be almost the same but for the subtraction you will subtract $sumSeconds of both times and then convert the result.

Carbon is what you need, it's integrate with laravel by default.

http://carbon.nesbot.com/docs/

using its addHours() and subHours() function to achieve your requirements.

$times = [
  "9:00:00",
  "8:00:00",
  "9:00:00",
];

// Converting the time to seconds makes calculations
// more simple and easier to understand.
function timeToSeconds($time) {
  list($hours, $minutes, $seconds) = explode(":", $time);

  return ($hours * 60 * 60) + ($minutes * 60) + $seconds;
}


// Let's use this to convert say 300s into 00:05:00
function formatSecondsAsHMI($seconds) {
  return sprintf(
    '%02d:%02d:%02d',
    floor($seconds / 3600),
    floor($seconds / 60 % 60),
    floor($seconds % 60)
  );
}

// Add an array of times together and return the formatted string hh:mm:ss
function addTimes($times) {
  $seconds = array_sum(array_map(function ($time) {
    return timeToSeconds($time);
  }, $times));

  return formatSecondsAsHMI($seconds);
}

// Subtract an array of times. Order of array important.
// Subtracts 0 from 1 from 2 where 0,1,2 are array keys
// i.e. [03:00:00, 10:00:00] would subtract 3 from 10 = 07:00:00
function subtractTimes($times) {
  $times = array_map(function($time) {
    return timeToSeconds($time);
  }, $times);

  return array_reduce($times, function($carry, $item) {
    return ($item - $carry);
  });
}

// Now just add the times together and subtract the result from 45
echo subtractTimes([addTimes($times), '45:00:00']);