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 age of somu is one - third his father ' s . 10 years back he was one - fifth of his father ' s age . what is his persent age ? 
Options: a ) 11 , b ) 13 , c ) 14 , d ) 12 , e ) 20
e

Problem: x varies inversely as square of y . given that y = 3 for x = 1 . the value of x for y = 7 will be equal to : 
Options: a ) 3 , b ) 6 , c ) 1 / 9 , d ) 1 / 3 , e ) 9 / 49
e

Problem: the sum of the average ( arithmetic mean ) of the even integers from 0 to 100 inclusive and the average ( arithmetic mean ) of the even integers from 0 to 50 inclusive ? 
Options: a ) 15 , b ) 125 , c ) 25 , d ) 75 , e ) 50

d