Probability question for those who paid attention in Maths class unlike myself.

Hi,

I have a question which is probably quite easy for people who are smarter than me,so therefore everyone should be able to answer.

When playing Keno in a game with 80 numbers with 20 unique numbers drawn out, what is the probability of there being-
A: More than 10 numbers drawn from the lower half(ie 1-40),
B: More than 10 drawn from the upper half(ie 41-80) or
C: Exactly 10 numbers drawn from each group.

Thank you.

A: More than 10 numbers drawn from the lower half(ie 1-40), ... B: More than 10 drawn from the upper half(ie 41-80) or
I guess A and B would be the same probability for any one draw are mutually exclusive for a draw of only 20 numbers.

I'll leave it to the math types to say things like Combination and Permutation and Factorial, but isn't it 20 factorial minus 10 factorial divided by 20 factorial?

(Math types get impressed when you say things like factorial dodecahedron or Tolstoy).

More than 10 in lower half: 39.8378485
More than 10 in upper half: 39.8378485
Exactly 10 in each half: 20.324303
From https://wizardofodds.com/keno/kenoapx8.html