In how many ways can 21 English and 19 Hindi books be placed in a row so that no two Hindi are together?
In how many ways can 19 identical books on English and 17 identical books on Hindi be placed in a row on a shelf so that two books on Hindi may not be together ?
The number of ways in which 6 Telugu, 4 Hindi and 3 English books be placed in a row on a shelf so that the books of the same subject should remain together is