Regarding applicability long term capital gain

Khizar khan (10 Points)

28 June 2019  
Suppose Mr. A have two Residentails houses both are ancestral and one of the house sold in 2016-17 for Rs 15,00,000 and same day the value of house according to government is Rs 16,00,000. he didn't file any income tax return for any of the finanacial year till now and he is a government employee also then in financial year 2018-19 he had purchased agriculture land for Rs 17,00,000.
My query is that is he have to pay any LTCG or not, if yes than how much.
What is the procedure for the same will be followed.