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'.

Input: Consider Input: Problem: find value for x from below equation ? x + 1 = 4 
Options: a ) - 5 , b ) - 4 , c ) 4 , d ) 3 , e ) 2

Output: d


Input: Consider Input: Problem: a 20 litre mixture of milk and water contains milk and water in the ratio 3 : 2 . 10 litres of the mixture is removed and replaced with pure milk and the operation is repeated once more . at the end of the two removal and replacement , what is the ratio t of milk and water in the resultant mixture ? 
Options: a ) 17 : 3 , b ) 9 : 1 , c ) 3 : 17 , d ) 5 : 3 , e ) 11 : 2

Output: b


Input: Consider Input: Problem: the average of 9 observations was 6 , that of the 1 st of 5 being 10 and that of the last 5 being 8 . what was the 5 th observation ? 
Options: a ) 36 , b ) 12 , c ) 15 , d ) 17 , e ) 18


Output: a