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

[Q]: Problem: if a 1 mm thick paper is folded so that the area is halved at every fold , then what would be the thickness of the pile after 50 folds ?
[A]: 1 billion km', 'e ) none'


[Q]: Problem: the ratio of a to b is 4 to 5 , where a and b are positive . if x equals a increased by 25 percent of a , and m equals b decreased by 60 percent of b , what is the value of m / x ?
[A]: 2 / 5


[Q]: Problem: if log 10 5 + log 10 ( 5 x + 1 ) = log 10 ( x + 5 ) + 1 , then x is equal to :
[A]:
3