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: if ( 1 – 1.5 ) n = 1 , then n = 
Options: a ) − 400 , b ) − 140 , c ) − 2 , d ) 4 , e ) 400
c

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: a man is 30 years older than his son . in four years , his age will be twice the age of his son . the present age of this son is 
Options: a ) 22 years , b ) 23 years , c ) 24 years , d ) 25 years , e ) 26 years

e