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

[Q]: Problem: a cistern 5 m long and 4 m wide contains water up to a depth of 1 m 25 cm . the total area of the wet surface is :
[A]: 42.5 m 2

[Q]: Problem: two trains of length 100 meters and 200 meters are 450 meters apart . they are moving towards each other on parallel tracks , at speeds of 90 km / h and 72 km / h . after how many seconds will the trains meet ?
[A]: 10

[Q]: Problem: arjun started a business with rs . 20,000 and is joined afterwards by anoop with rs . 30 , 000 . after how many months did anoop join if the profits at the end of the year are divided equally ?
[A]:
4