In a library, 2/5 of the total books are Hadith books. Three fourths (3/4) of the remaining books are Mathematics books. The 642 books remaining are on other subjects. Find the total number of books in the library?
In a library, 2/5 of the total books are Hadith books. Three fourths (3/4) of the remaining books are Mathematics books. The 642 books remaining are on other subjects. Find the total number of books in the library?
Explanation
Let's denote the total number of books as x.
Hadith books = 2/5 × x = 2x/5
Remaining books = x - 2x/5 = 3x/5
Mathematics books = 3/4 × 3x/5 = 9x/20
Books on other subjects = 3x/5 - 9x/20
= (12x - 9x)/20
= 3x/20
Given that the number of books on other subjects is 642:
3x/20 = 642
x = 642 × 20/3
x = 4280