The task is to generate the correct answer for a given math problem.

[EX Q]: Problem: the average of first 5 multiples of 5 is
[EX A]: 1

[EX Q]: Problem: two numbers are in the ratio 3 : 5 . if 9 be subtracted from each , they are in the ratio of 1 : 2 . the first number is :
[EX A]: a ) 27

[EX Q]: Problem: 20 buckets of water fill a tank when the capacity of each bucket is 13.5 litres . how many buckets will be required to fill the same tank if the capacity of each bucket is 9 litres ?
[EX A]:
30