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'.

Problem: the average of 5 quantities is 9 . the average of 3 of them is 4 . what is the average of remaining 2 numbers ?
Options: a ) 16.5 , b ) 10 , c ) 8 , d ) 9.5 , e ) none of these
a

Problem: the tax on a commodity is diminished by 40 % but its consumption is increased by 25 % . find the decrease percent in the revenue derived from it ?
Options: a ) 18 % , b ) 72 % , c ) 25 % , d ) 12 % , e ) 52 %
c

Problem: the difference between the ages of two persons is 10 years . fifteen years ago , the elder one was twice as old as the younger one . the present age of the elder person is ?
Options: a ) 35 yr , b ) 25 yr , c ) 20 yr , d ) 30 yr , e ) 40 yr
a