The task is to generate the correct answer for a given math problem.

[EX Q]: Problem: a train running at the speed of 40 km / hr crosses a pole in 9 seconds . what is the length of the train ?
[EX A]: 100 meter

[EX Q]: Problem: at a certain fruit stand , the price of each apple is 40 cents and the price of each orange is 60 cents . mary selects a total of 30 apples and oranges from the fruit stand , and the average ( arithmetic mean ) price of the 30 pieces of fruit is 56 cents . how many oranges must mary put back so that the average price of the pieces of fruit that she keeps is 52 cents ?
[EX A]: 1

[EX Q]: Problem: heinz produces tomato puree by boiling tomato juice . the tomato puree has only 20 % water while the tomato juice has 90 % water . how many liters of tomato puree will be obtained from 25 litres of tomato juice ?
[EX A]:
3.125 liters .