Question 419101
percent	----------------	quantity		
40	----------------	20
100	----------------	x
60	----------------	20+x

......
40*20+100*x=60(	20+x)
800+100	x=1200+60x					
100x-60x=1200-800					
40x=400										
/	40									
x=10	liters of 100 % alchohol