text: <START_QUESTION> many was working in a chemistry lab with a mixture of chemicals that was 90 % water and weighed 20 pounds. after returning to the lab from a weekend break, she calculated the mixture was now 50 % water. how much does the mixture now weigh? for purposes of this puzzle, assume the non - water part of the mixture was not affected by evaporation. <END_QUESTION>
  <ANSWER> 12 pounds <END_ANSWER><|endoftext|>