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'.

[Q]: Problem: if 3 x – 5 y = 5 and x / x + y = 5 / 7 , then what is the value of x – y ? 
Options: a ) 9 , b ) 6 , c ) 4 , d ) 3 , e ) none of these
[A]: d


[Q]: Problem: in a group of ducks and cows , the total number of legs are 22 more than twice the no . of heads . find the total no . of buffaloes . 
Options: a ) 11 , b ) 12 , c ) 13 , d ) 15 , e ) 16
[A]: a


[Q]: Problem: how many kg of pure salt must be added to 100 kg of 10 % solution of salt and water to increase it to a 25 % solution ? 
Options: a ) a ) 6.7 , b ) b ) 1.3 , c ) c ) 9.6 , d ) d ) 20 , e ) e ) 7.9
[A]:
d