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'.

[EX Q]: Problem: the sum of ages of 5 children born at the intervals of 3 years each is 80 years . what is the age of the youngest child ? 
Options: a ) 3 years , b ) 4 years , c ) 6 years , d ) 7 years , e ) 10 years
[EX A]: e

[EX Q]: Problem: a cyclist rides a bicycle 8 km at an average speed of 10 km / hr and again travels 10 km at an average speed of 8 km / hr . what is the average speed for the entire trip ? 
Options: a ) 9.28 , b ) 8.48 , c ) 8.78 , d ) 8.98 , e ) 9.18
[EX A]: c

[EX Q]: Problem: the average of 10 consecutive integers is 15 . then , 9 is deducted from the first consecutive number , 8 is deducted from the second , 7 is deducted form the third , and so on until the last number which remains unchanged . what is the new average ? 
Options: a ) 10 , b ) 10.5 , c ) 11 , d ) 11.5 , e ) 12
[EX A]:
b