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 ?
Output (English): 640