Question 635066
  <pre><font face = "Tohoma" size = 3 color = "indigo"><b> 
Hi,
From 4 red, 5 green, and 6 black ball pens,
3 from each color selected
 {{{4C3*5C3*6C3 = 4*10 *20 }}} ways of selecting the nine pens 
nCx = {{{n!/(x!(n-x)!)}}}