What's described can happen in the following waysAll 3 tiles match on a letterAll 3 tiles match on a number1 of the tiles match both the other two, but the other two do not matchThere are three ways that the previous line can occur[(1,2),(1,3)],[(1,2),(2,3)],[(1,3),(2,3)]
P[3 tiles match letter]=424323=12123P[3 tiles match number]=12123P[2 tiles match the other tile but not each other]=824423=43123P[what's described]=2×12123+3×43123=123+423=523
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