yah 21 is correct .
the alternate numbers are related.
4 Answers
					
			Anirudh Narayanan
					·2009-05-08 02:38:02
			
			
			it wud be helpful if u tell the logic cos i don't have the solutions
					
			Manas
					·2009-05-08 02:45:41
			
			
		hey see the alternate nos . there differences are in AP.
so
u get the series as 6 9 14 and then 21.
