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

Ex 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 ?

Ex Output:
$ 5040

Ex Input:
Problem: a train running at the speed of 70 km / hr crosses a pole in 9 sec . what is the length of the train ?

Ex Output:
175 m

Ex Input:
Problem: if the selling price of 60 articles is equal to the cost price of 30 articles , then the loss or gain percent is :

Ex Output:
50