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: a rower whose speed is 2.5 km / hr in still water rows to a certain point upstream and back to the starting point in a river which flows at 0.5 km / hr . what is the rower ' s average speed ( in km / hr ) for the total journey ?
Options: a ) 2.2 , b ) 2.3 , c ) 2.4 , d ) 2.5 , e ) 2.6
[A]: c

[Q]: Problem: 5.005 / 4.004 =
Options: a ) 1.05 , b ) 1.50015 , c ) 1.501 , d ) 1.5015 , e ) 1.25
[A]: e

[Q]: Problem: 5 is added to a certain number , the sum is multiplied by 5 , the product is divided by 5 and 5 is subtracted from the quotient . the remainder left is half of 60 . what is the number ?
Options: a ) 21 , b ) 20 , c ) 2 , d ) 30 , e ) 45
[A]:
c