TASK DEFINITION: The task is to generate the correct answer for a given math problem.
PROBLEM: Problem: a bullet train covers a distance in 50 min , if it runs at a speed of 48 kmph on an average . the speed at which the bullet train must run to reduce the time of journey to 40 min will be .

SOLUTION: 60 kmph

PROBLEM: Problem: a train 150 m long is running at a speed of 68 kmph . how long does it take to pass a man who is running at 8 kmph in the same direction as the train ?

SOLUTION: 9 sec

PROBLEM: Problem: how many zeroes are there at the end of the number n , if n = 90 ! + 180 ! ?

SOLUTION:
21