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'.

[EX Q]: Problem: 8597 - ? = 7429 - 4358
Options: a ) 3567 , b ) 6424 , c ) 6835 , d ) 5526 , e ) none of these
[EX A]: d

[EX Q]: Problem: if 1 + 3 = 10 ; 3 + 5 = 52 ; 5 + 7 = 174 then 7 + 11 = ?
Options: a ) 354 , b ) 225 , c ) 654 , d ) 741 , e ) 464
[EX A]: e

[EX Q]: Problem: a rower whose speed is 4 km / hr in still water rows to a certain point upstream and back to the starting point in a river which flows at 2 km / hr . what is the rower ' s average speed ( in km / hr ) for the total journey ?
Options: a ) 6 , b ) 4 , c ) 9 , d ) 3 , e ) 2
[EX A]:
d