a boy has 3 library tickets and 8 books are of his interest. Of these 8,he doesn't want to borrow maths part 2, unless maths part 1 is also borrowed? In how many ways can he choose the 3 books to be borrowed ?

Various cases possible are:

(i) **When Maths part-I is borrowed:** Here, the boy may borrow maths part-II. So, he has to select 2 books out of the remaining 7 books, which can be done in ways.

(ii) **When maths part-I is not borrowed:** Here, the boy will not borrow maths part-II. So, he has to select 3 books from the remaining 6 books, which can be done in ways.

âˆ´Total number of ways = +

= 21 + 20

= **41**

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