suppose R ={1, 3, 5, 7, 9, 11, 15, 17} and D= {3, 6, 9, 12, 15, 18, 21, 24, 27}. what is RnD

Answer 1

I assume you meant : R ∩ D

What numbers do you see that appear in both R AND D

list them in set notation.

Answer 2

If by that "n" you mean ∩, it just means the datasets of the values of R AND D.