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

[EX Q]: Problem: convert 2 / 5 to a decimal
[EX A]: 0.4

[EX Q]: Problem: a sum was put at simple interest at a certain rate for 10 years . had it been put at 5 % higher rate , it would have fetched rs . 600 more . what was the sum ?
[EX A]: rs . 1200

[EX Q]: Problem: a certain fraction is equivalent to 2 / 5 . if the numerator of the fraction is increased by 4 and the denominator is doubled , the new fraction is equivalent to 1 / 3 . what is the difference of the numerator and denominator of the original fraction ?
[EX A]:
9