Please Help Math

Question

Let U={1, 2, 3, 4, 5, 6, 7, 8, 9} and A={1}. Find the set Ac .

Answer 1

I'm not certain what Ac is but I suspect it's the complement of A, or ~A.  If it's something else, please clarify.

 

∼A = U - A = {1, 2, 3, 4, 5, 6, 7, 8, 9} - {1} = {2, 3, 4, 5, 6, 7, 8, 9}