instruction:
The task is to generate the correct answer for a given math problem.
question:
Problem: a bullet train covers a distance in 50 min , if it runs at a speed of 48 kmph on an average . the speed at which the bullet train must run to reduce the time of journey to 40 min will be .
answer:
60 kmph


question:
Problem: a swimmer can swim in still water at 4 km / h . if the speed of the water current is 2 km / h , how many hours will the swimmer take to swim against the current for 5 km ?
answer:
2.5


question:
Problem: when the perimeter of a regular polygon is divided by 5 , the length of a side is 25 . what is the name of the polygon ? what is the perimeter ?
answer:

125', 'b ) 126', 'c ) 127', 'd ) 128', 'e ) 129'