In this task, you need to answer the given multiple-choice question on the general math. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Example Input: Problem: ( 0.15 ) ( power 3 ) - ( 0.1 ) ( power 3 ) / ( 0.15 ) ( power 2 ) + 0.015 + ( 0.1 ) ( power 2 ) is :
Options: a ) 0.68 , b ) 0.08 , c ) 0.05 , d ) 0.06 , e ) none of them
Example Output: c

Example Input: Problem: if x / 4 years ago roger was 14 years old and x / 4 years from now he will be 4 x years old , how old will he be 6 x years from now ?
Options: a ) 32 , b ) 39 , c ) 30 , d ) 40 , e ) 28
Example Output: b

Example Input: Problem: if a 2 + b 2 + c 2 = 213 and ab + bc + ca = 6 , then a + b + c is
Options: a ) 14 , b ) 20 , c ) 15 , d ) 32 , e ) 64
Example Output:
c