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

Example Input: Problem: 1370 , x , 1070 , - 180 , - 6430
Example Output: 1320

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

Example Input: Problem: if the price of a certain computer increased 30 percent from c dollars to 351 dollars , then 2 c =
Example Output:
540