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

Ex Input:
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 .

Ex Output:
60 kmph

Ex Input:
Problem: the perimeter of a triangle is 36 cm and the inradius of the triangle is 2.5 cm . what is the area of the triangle

Ex Output:
b ) 45

Ex Input:
Problem: the height of a triangle is decreased by 5 % and its base increased by 10 % . its area will

Ex Output:
increase by 4.5 %', 'd ) increase by 25 %', 'e ) none of these'