Showing date different in blade laravel 5.4

I am trying to show different between 2 dates. My database fields are proj_starts and proj_end. I want to calculate it in blade. It show me error.

<td>
                <?php
                $to = \Carbon\Carbon::createFromFormat('Y-m-d', ?>  <?php );
                $from = \Carbon\Carbon::createFromFormat('Y-m-d', ?>  <?php );
                $diff_in_days = $to->diffInDays($from);
                echo $diff_in_days;
                ?>
             </td>

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