In how many ways can 10 married couples sit around a table if?

In how many ways can 10 married couples sit around a table if


a) there are no restrictions?


b) the women will seat together?


c) the wives seat beside their husband?In how many ways can 10 married couples sit around a table if?
a. for 20 people, the formula is (n-1)!. so there are 19! ways.





b. If by defining the women seat together as the women sit on one side of the table and the men on the area then there are (9!)(10)! ways





c. there are 10 couples, so there are 9! ways.