I am nowhere near being an expert on PHP, but it appears that your script is looking for something that is not being sent
Your PHP is checking to see if
submit is included in the request
if(isset($_POST['submit'])){
But the AJAX making the request does not appear to have
submit in the data being sent
$.ajax({
url:"hourspage.php",
type:"POST",
data:{
hourPHP:hoursf,
ratePHP:ratef,
datePHP:datef
},
success: function(response){
$('#response').html(response);
console.log(data);
},
datatype:"text"
});