<PRE><B>Question 461379</B>
Assume that two particular boys as a single boy and also two girls as a single girl.

so, 4 boys and 9 girls, two boys can also arrange by 2! ways , similarly two girls can also arrange by 2! ways.


number of ways when they are together = 13! *2*2 


number of ways when there is no restriction = 15!


required number of ways when they are not together = 15! - 13! * 2*2



Everyone is welcome to get free help online:   sudhanshu.cochin@gmail.com</PRE>