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

Ex Input:
Problem: a swimmer can swim in still water at 4 km / h . if the speed of the water current is 2 km / h , how many hours will the swimmer take to swim against the current for 5 km ?

Ex Output:
2.5


Ex Input:
Problem: what is the sum of the multiples of 4 between 63 and 151 inclusive ?

Ex Output:
233


Ex Input:
Problem: the mean of 50 observations was 36 . it was found later an observation 48 was wrongly taken as 23 . the corrected new means is :

Ex Output:

36.5