Integer conversion on Controller Laravel

I have the following data in the controller:

$sheets = printerChange::select('folhas');
$sheetsNew = printerChange::select('folhasnew');
$sheetsCompare = (int)$sheetsNew;

if(!is_null($sheetsCompare > 0)){
   $calcSheets->folhasnew = $request->folhas - $calcSheets->folhas;
}
else{
   $calcSheets->folhasnew = $request->folhas;
}

When I run, the following error appears in my browser:

  

Object of class Illuminate \ Database \ Eloquent \ Builder could not be converted to int

I searched a lot on the internet and could not find anything that would help me, I saw several forms of conversion but none helped me to this point.

Is something wrong with my syntax?

PS: As a database I'm using PostgreSQL.