capital gain

Krk (26 Points)

10 May 2007  
I had purchased plot area 600square feet  for RS 80000/- in 1999-00, In the year  2005-06 i constructed ground plus 1st floor for Rs 5.4lakhs.  In the same year i have sold half of the 1st floor i.e 1 room for Rs 5.4lakhs.Total area of the 1st floor is 846square feet.I have also incurred  RS 40000/- for cost of flooring for ground & 1st floor.

i want to know what will be the cost of acquisition for room 1 which i have sold.  sale consideration 5.4lakhs.for room one.