t variable error meaning in php

1//Parse error: syntax error, unexpected T_STRING, expecting T_VARIABLE
2//Occurs when there is a variable that is not allowed. e.g Missed a 
3//($)dollar sign before the variable name or (;)semcolon at the end.
4
5<?php
6  $a = 5
7  $b = 7;        // Error happens here.
8  print $b;
9?>
10