I found a solution,hope it works for others as well
visit this website -> https://repogen.simplylinux.ch/ and choose your 'country' and 'release' along with necessary 'branches' and 'updates' and go to end of the page till 'Generate list' button and click it to get your new sources.list
copy the text in 'sources list' text field and open sources.list file in /etc/apt/ in local file system and open in editable mode i.e., in sudo mode to edit, replace the current data with newly copy data and save it
open terminal enter these commands : sudo apt-get update sudo apt-get install lib32stdc++6
you are done. Now, just check if the problem with making AVD is gone or not.
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