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

Example Input: Problem: if 1.5 cm of a pencil is purple , 0.5 cm of the remaining is black and the remaining 2 cm is blue , what is the total length of the pencil ?
Example Output: 4 cm

Example Input: Problem: the speed of a car is 85 km in the first hour and 45 km in the second hour . what is the average speed of the car ?
Example Output: 65 kmph

Example Input: Problem: if 20 % of x is 15 less than 15 % of 1500 , then x is ?
Example Output:
105