On the eve of Holi festival, a group of 15 friends greeted every other friend by sending greeting cards. Find the number of cards purchased by group.

On the eve of Holi festival, a group of 15 friends greeted every other

1.	On the eve of Holi festival, a group of 15 friends greeted every other friend by sending greeting cards. Find the number of cards purchased by group.
A.	156
B.	144
C.	210
D.	320
Answer» D. 320