IT return doubt

Hi

Can anyone advise on how to calculate capital gains on an ancestral property in the below notice. It was acquired years back. The property is in the name of 5 members however notice in one person.

Dear KANJIRANGADAN PADMINI - Income Tax Department has received information about Sale of immovable property of 3362500 relating to XXXXX8319X in FY 2018-19. However, as per records available, ITR for AY 2019-20 has not been filed. Please file your ITR by 30.9.2020. You can view transaction details and submit online response under e-Campaign tab on Compliance Portal (https://compliance.insight.gov.in) - ITD