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

Example Input: Problem: if the personal income tax rate is lowered from 46 % to 32 % , what is the differential savings for a tax payer having an annual income before tax to the tune of $ 36000 ?
Example Output: $ 5040

Example Input: Problem: a no . when divided by 281 gives a remainder 160 , what remainder will be obtainedby dividingthe same no . 21 ?
Example Output: 21

Example Input: Problem: a train running at the speed of 27 km / hr crosses a post in 20 seconds . what is the length of the train ?
Example Output:
150