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

[EX Q]: Problem: in a group of 150 readers who read science fiction or literacy works or both , 120 read science fiction and 90 read literacy works . how many read both science fiction and literacy works ?
[EX A]: 60

[EX Q]: Problem: a jar contains a mixture of ab in the ratio 4 : 1 . when 40 l of mixture is replaced with liquid b , ratio becomes 2 : 3 . how many liters of liquid a was present in mixture initially .
[EX A]: 64

[EX 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 ?
[EX A]:
1 billion km', 'e ) none'