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: how many paying stones , each measuring 2 1 / 2 m * 2 m are required to pave a rectangular court yard 20 m long and 16 1 / 2 m board ? 
Options: a ) 66 , b ) 18 , c ) 16 , d ) 10 , e ) 15
[A]: a


[Q]: Problem: what is the least number which should be added to 5432 so that the sum is exactly divisible by 5 , 6 , 4 , and 3 ? 
Options: a ) 16 , b ) 22 , c ) 28 , d ) 34 , e ) 40
[A]: c


[Q]: Problem: a man can row 4.2 km / hr in still water . it takes him twice as long to row upstream as to row downstream . what is the rate of the current ? 
Options: a ) 1.9 , b ) 1.7 , c ) 1.4 , d ) 1.5 , e ) 1.1
[A]:
c