Mainstream media polls approval rate 29%. Total votes actually cast for trump 74,222,958, 46.8 percent. Margin of lying = 29% - 46.8% = minus 17.8. They robbed Trump 17.8 percentage popularity in that poll.
Mainstream media polls approval rate 76%. Total votes claimed to have been cast for Biden 81,283,098, or 51.3 percent. Margin of lying = 76% - 51.3% = 24.7%. They deliberately posted a falsely overblown poll number for Biden in that poll.
Therefore actual number Biden votes just remove 24.7% (margin of lying) to know what is on the ground. That 24.7 is fake mailing votes. And add 17.8 percent on Trump to get actual number of heads who will show up to vote Trump.