Definition: In this task, you need to provide the correct option for a given problem from the provided options.

Positive Example 1 -
Input: Problem: jo ' s collection contains us , indian and british stamps . if the ratio of us to indian stamps is 6 to 2 and the ratio of indian to british stamps is 5 to 1 , what is the ratio of us to british stamps ? 
Options: a ) 5 : 1 , b ) 30 : 2 , c ) 15 : 2 , d ) 20 : 2 , e ) 25 : 2
Output: b

Positive Example 2 -
Input: Problem: if 6 and 8 are factors of 60 n , what is the minimum value of n ? 
Options: a ) 2 , b ) 4 , c ) 7 , d ) 14 , e ) 56
Output: b

Negative Example 1 -
Input: Problem: 100 people are attending a newspaper conference . 40 of them are writers and more than 38 are editors . of the people at the conference , x are both writers and editors and 2 x are neither . what is the largest possible number of people who are both writers and editors ? 
Options: a ) 21 , b ) 24 , c ) 28 , d ) 30 , e ) 32
Output: d

Negative Example 2 -
Input: Problem: sachin is younger than rahul by 7 years . if the ratio of their ages is 5 : 12 , find the age of sachin 
Options: a ) 9 , b ) 24.8 , c ) 2 , d ) 3 , e ) 5
Output: b

Now complete the following example -
Input: Problem: the number of people who purchased book a is twice the number of people who purchased book b . the number of people who purchased both books a and b is 500 , which is twice the number of people who purchased only book b . what is the number of people b who purchased only book a ? 
Options: a ) 250 , b ) 500 , c ) 750 , d ) 1000 , e ) 1500
Output: 


Output: d