Capital gains commercial

Sir with due respect I want to know that I have purchased a plot in commttee area for Rs 20.00. Lac in the f.y 2012-13 and in the said year I have made the construction for Rs 25.00 Lac and now in the f.y the above said land with building has been sold for Rs 62.00 Lac Sir I want to know how to calculate the capital gains on the said transaction and how many capital gains tax comes on the above said transaction.Thanks