Six girls met and they greeted each other with a "Hello". How many times was the word "Hello" 
said ?
(a) 6
(b) 15
(c) 30
(d) 45
Six girls met and they greeted each other with a "Hello". How many times was the word "Hello" 
said ?
(a) 6
(b) 15
(c) 30
(d) 45