Answers for "Parse error: syntax error, unexpected token "=", expecting ";" in C:\xampp\htdocs"

Parse error: syntax error, unexpected '?' in /opt/lampp/htdocs/Tack.php on line 2

Parse error: syntax error, unexpected '?' in /opt/lampp/htdocs/Tack.php on line 2

Parse error: syntax error, unexpected token "=", expecting ";" in C:\xampp\htdocs

Parse error: syntax error, unexpected token ";", expecting ")" in C:\xampp\htdocs\tanveer\index.php on line 10