Passengers are to travel by a double decked bus which can accommodate 13 in the upper deck and 7 in the lower deck. Find the number of ways that they can be distributed if 5 refuse to sit in the upper deck and 8 refuse to sit in the lower deck.

Passengers are to travel by a double decked bus which can accommodate 13 in the upper deck and 7 in the lower deck.The number of ways that they can be divided if 5 refuse to sit in the upper deck and 8refuse to sit in the lower deck,is

Passengers are to travel by a double decker bus which can accomodate in upper deck and in lower deck.The number of ways that the passengers are distributed is

A double-decker bus carry (u+l) passengers,u in the upper deck and l in the lower deck. Find the number of ways in which the u+l passengers can be distributed in the two decks,if r(<=l) particular passengers refuse to go in the upper deck and s(<=u) refuse to sit in the lower deck.

Find the number of ways in which 8 distinct toys can be distributed among 5 children.

Find the number of ways in which one can post 5 letters in 7 letter boxes.

Find the number of ways in which four persons can sit on six chairs.

The number of ways in which 5 distinct toys can be distributed among 8 children is

Why are passengers travelling in a double decker bus allowed to stand in a lower deck, but not in the upper deck?