two friends A and B meet at a point between their houses.Generally they leave their respective houses at 7:50 AM and meet at 8:05 AM.one day B started at 7:55 AM amd met A at 8:07 AM.next day if Now B has to travel to A's house how much time will it take?

Let the speed of A be A km per minute, speed of B be B km per minute
Distance between the houses of A and B = 15(A+B)

On that particular day, distance travelled by A and B together = (8:07 - 7:55)B + (8:07 - 7:50)A = 17A + 12B
=> 15A + 15B = 17A + 12B => 3B = 2A => A = 3B/2

So, time B needs to travel to A's house = 15(A + B)/B = 15(5B/2)/B = 75/2 = 37.5 minutes