A boy walks to his school at adistance of 6km withconstant speed of 2.5 kmph and walks back with a constant speed of 4 kmph. His average speed for round trip expressed in kmph is

A boy walks to his school at adistance of 6km withconstant speed of 2.

1.	A boy walks to his school at adistance of 6km withconstant speed of 2.5 kmph and walks back with a constant speed of 4 kmph. His average speed for round trip expressed in kmph is
Answer» `24//13` `40//13` 3 `1//2` ANSWER :B