PHP - Parse error: syntax error, unexpected T_VARIABLE, expecting ',' or ';' in ...

<?php

	$mensa = $myuser['Alert_mens'];

	if ($myuser['Alert_active'] > 0 )

	  echo '<div class="container-fluid"><div class="alert alert-warning alert-dismissible" role="alert">

	    <button type="button" class="close" data-dismiss="alert" aria-label="Close"><span aria-hidden="true">&times;</span></button>

	    <strong>'$mensa'</strong></div></div>' //Esta es la linea 80

	?>

<?php

$mensa = $myuser['Alert_mens'];

$c = $myuser['Alert_active'];

if ( $c > 0 ):

?>

<div class="container-fluid">

	<div class="alert alert-warning alert-dismissible" role="alert">

		<button type="button" class="close" data-dismiss="alert" aria-label="Close">

			<span aria-hidden="true">

				×

			</span>

		</button>

		<strong>

			<?php echo $mensa; ?>

		</strong>

	</div>

</div>

<?php

endif;

?>