It's all incredibly simple! No one can do simple math problems ...
The government reported registered voter turnout for the 2020 election turnout at 66% (average 59% historically). Take that percentage from the 216 million registered US voters, this gives you 142 560,000 actual supposed voters. Take that number and subtract the 74,000,000 votes Trump got and that leaves 68,560,000 votes left over for Biden. So, where'd the other 15,000,000+- votes come from? Because according to the governments numbers, there's that many extra votes.
I KNOW everyone hates word problems, but if you are paying off a student loan from a university and this is hard for you, then I'd get a lawyer and sue them for defrauding you. There's no need for hyperbole or rhetoric, it's basic math.
Your problem is that you can't do word problems. There are 216,000,000 registered voters. Thats the pool you draw from. Sue that college!