In this task, you need to answer the given multiple-choice question on the gain. Gain is the value by which to multiply the input. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

[EX Q]: Problem: from january 1 , 1991 , to january 1 , 1993 , the number of people enrolled in health maintenance organizations increased by 20 percent . the enrollment on january 1 , 1993 , was 50 million . how many million people , to the nearest million , were enrolled in health maintenance organizations on january 1 , 1991 ? 
Options: a ) 38 , b ) 39 , c ) 40 , d ) 41 , e ) 42
[EX A]: e

[EX Q]: Problem: if 28 % of a number exceeds 18 % of it by 7.2 , then find the number ? 
Options: a ) 50 , b ) 34 , c ) 55 , d ) 60 , e ) 90
[EX A]: e

[EX Q]: Problem: calculate how many seconds it will take for 4 bells to toll together again , given that they begin to toll together respectively at the intervals of 9 , 12 , 15 and 18 seconds ? 
Options: a ) 186 , b ) 130 , c ) 180 , d ) 181 , e ) 120
[EX A]:
c