Question 419707
100	----------------	x
30	----------------	10-x
50.00%	----------------	10		
...
100x	+30(10	-x)	=	50	*	10
100x	+300-30	x=	500		
100x-30	x=500-	300		
70	x	-		=	200							
/70											
x=2.86	liters of 100.00%	

2.86 liters of 30 % will have to be drained off.