$field1 = “”; // replace with the value of the first field
$field2 = “”; // replace with the value of the second field
$field3 = “”; // replace with the value of the third field

$totalFields = 0;
$sum = 0;

if (!empty($field1)) {
$totalFields++;
$sum += $field1;
}

if (!empty($field2)) {
$totalFields++;
$sum += $field2;
}

if (!empty($field3)) {
$totalFields++;
$sum += $field3;
}

$average = ($totalFields > 0) ? ($sum / $totalFields) : “”;

return “The average is: ” . $average;