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

Example Input: Problem: calculate the sum of first 60 natural numbers .
Example Output: 1830

Example Input: Problem: john invests $ x at the semi - annual constant compounded rate of 2 percent and also does $ 20,000 at the quarterly constant compounded rate of 4 percent . if the interests are the same after 1 year , what is the value of x ? ?
Example Output: 40,402

Example Input: Problem: a trained covered x km at 90 kmph and another 2 x km at 20 kmph . find the average speed of the train in covering the entire 3 x km .
Example Output:
27