There are 15 buses running between Mirpur and Motijheel. In how many ways can a man go to Motijheel and return by a different bus?

There are 15 buses running between Mirpur and Motijheel. In how many ways can a man go to Motijheel and return by a different bus?

A 280

B 310

C 240

D 210

Solution

Correct Answer: Option D