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

[Q]: Problem: the smallest value of n , for which n + 2 is not a prime number , is
[A]: 2,4


[Q]: Problem: a train passes a station platform in 30 sec and a man standing on the platform in 20 sec . if the speed of the train is 54 km / hr . what is the length of the platform ?
[A]: 60 


[Q]: Problem: in what time will a train 175 m long cross an electric pole , it its speed be 180 km / hr ?
[A]:
3.