Task: Question Answering
Input (English): Problem: the ratio , by volume , of soap to alcohol to water in a certain solution is 20 : 50 : 80 . the solution will be altered so that the ratio of soap to alcohol is doubled while the ratio of soap to water is halved . if the altered solution will contain 100 cubic centimeters of alcohol , how many cubic centimeters of water will it contain ? 
Options: a ) 520 , b ) 640 , c ) 700 , d ) 750 , e ) 800
Output (English): b