capital gains?

akshay jaiswal (ICAI) (35 Points)

24 July 2017  
Calculate capital gains if I had bought land at cost of 40 Lacs for 40000 sqft In FY 2015-16 and THEN SOLD part of that land of 4000sqft in FY2016-17 for consideration of Rs.9 Lacs,? Stamp duty is also Rs.9 lacs. 
Also tell me what should be the purchase cost?