10 people meet for a business lunch. Each person shakes hands once with each other person present. How many handshakes take place? Choose the correct choice from the following answers:
A) 30  B) 21  C) 18  D) 15  E) 45
the formula to count handshakes is n(n−1)2n(n−1)2   Where n is the number of people   =&gt; 10(9-1)/2 = 10*9/2 = 90/2= 
<gadget id="calculator">90/2</gadget>
<output>45</output>
45=&gt; the answer is 45(45)
<result>E</result>
10 people meet for a business lunch. Each person shakes hands once with each other person present. How many handshakes take place?