If (2 $$ \le $$ r $$ \le $$ n), then $${}^n{C_r}$$ + 2 . $${}^n{C_{r + 1}}$$ + $${}^n{C_{r + 2}}$$ is equal to

From a collection of 20 consecutive natural numbers, four are selected such that they are not consecutive. The number of such selections is

The number of all numbers having 5 digits, with distinct digits is

Out of 7 consonants and 4 vowels, words are formed each having 3 consonants and 2 vowels. The number of such words that can be formed is