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

Input: Consider Input: Problem: for any positive integer n , the sum of the first n positive integers equals n ( n + 1 ) / 2 . what is the sum of odd all the integers between 10 and 100 ?

Output: 2475

Input: Consider Input: Problem: a train 360 m long runs with a speed of 45 km / hr . what time will it take to pass a platform of 150 m long ?

Output: 40.8 sec

Input: Consider Input: Problem: on the first day of her vacation , louisa traveled 160 miles . on the second day , traveling at the same average speed , she traveled 280 miles . if the 160 - mile trip took 3 hours less than the 280 - mile trip , what was the average speed , in miles per hour ?
Output: 40