Steve and Jenn have three children: Jack age $23,$ David age $20$ and Kristen age $15.$ All three children lived at home the entire year of $2020.$ Jack graduated from college in $2019$ and will start medical school in $2021.$ In $2020,$ he worked sparingly as he studied for the medical school entrance exam but did earn $$5,000.$ Steve and Jenn provided $80\%$ of Jack's support during the year. Does Jack qualify as a dependent in $2020?$