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

Example Input: Problem: a cistern 5 m long and 4 m wide contains water up to a depth of 1 m 25 cm . the total area of the wet surface is :
Example Output: 42.5 m 2

Example Input: Problem: a lent rs . 5000 to b for 2 years and rs . 3000 to c for 4 years on simple interest at the same rate of interest and received rs . 1540 in all from both of them as interest . the rate of interest per annum is ?
Example Output: 7 %

Example Input: Problem: the average of first 5 multiples of 5 is
Example Output:
1