Question

Kiran read of a book. He found that there are still 80 pages left to read. Number of pages in the book are
A.250
B.100
C.150
D.200

Answer 1

Hint: In this question, we need to determine the total number of pages in the book such that 80 pages were left when Kiran already read $ \dfrac{3}{5} $ of a book. For this, we will establish a relation for the total number of pages in the book along with the conditions given in the question and solve it for the desired result.

Complete step-by-step answer:
Let the total number of the pages in the book be ‘x’.
According to the question, Kiran already read $ \dfrac{3}{5} $ of the book so, the number of the remaining pages (or the pages that still to be read by Kiran) is calculated as:
 $
\Rightarrow R = x - \;\dfrac{{3x}}{5} \\
   = \dfrac{{5x - 3x}}{5} \\
   = \dfrac{{2x}}{5} - - - - (i) \\
  $
Also, it is given in the question that the number of pages in the book left to be read by Kiran is 80. So, equating the established relation in equation (i) with 80, we get
 $ \dfrac{{2x}}{5} = 80 - - - - (ii) $
Solving the equation (ii) by cross-multiplying the terms to determine the value of the number of pages in the book.
 $
\Rightarrow \dfrac{{2x}}{5} = 80 \\
\Rightarrow 2x = 80 \times 5 \\
\Rightarrow x = \dfrac{{80 \times 5}}{2} \\
   = 40 \times 5 \\
   = 200 \\
  $
Hence, the total number of pages in the book that Kiran is reading is 200.
So, the correct answer is “Option D”.

Note: Here, total number of pages and the number of pages to be read includes the starting pages like acknowledgment, contents, etc. So, we don’t need to consider any other equations for those pages.