Hello Shalini,
If my maths is correct
Total No. of Employees in July 2007 = 277
New Joinees(July 2007 to 0

= 67
Total no. of employees July 2007 -2008 = 344
Less total no. of employees resigned = 45
Total Number of Employees in July 2008 = 299
Your figure for the same is
Total Number of Employees in July 2008 = 234
So what happened to the rest?
Have a nice day.
Narasimhan