All values should be undefined:
$vara = [+ $vara +] 
$varb = [+ $varb +] 
$c = [+ $c +] 
$d = [+ $d +] 
$e = [+ $e +] 
First of all assign a value:
[- $vara = '(this is the value in $vara)' -] 
Now we have some 'Umlaute':
[- $varb = "$vara äöü" -]
Now lets look what we are getting from this:
[+ $vara +] [+ $varb +]
And now a and b together: [+ "$vara$varb" +]
Here we have some HTML tags within the perl code, Embperl will delete them! Ok. 
[+ $c = 
 6 + 17  * 3 +]
Embperl will also translate HMTL escapes to the right characters i.e. $vara < 6 will get the perl expression $vara < 6: 
[- $e = 2 -]
[+ $d = $e < 6 +]
Now they should have a value
$vara = [+ $vara +] 
$varb = [+ $varb +] 
$c = [+ $c +] 
$d = [+ $d +] 
$e = [+ $e +]