+0  
 
+1
108
1
avatar+502 

last one

 Jun 12, 2021
 #1
avatar+35059 
+1

Not positive of this:

 

5 C 2 =  10 ways for the two balls to match their boxes

    the remaining 3 boxes can only have balls distributed to them in TWO ways (Out of a possible 6) where they do not match their boxes

 

10 * 2 = 20 ways for exactly two to match

 Jun 12, 2021

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