A person bought a certain number of books for Rs. 80. If he had bought 4 more books for the same sum, each book would have cost Rs. 1 less. What is the price of each book?
Correct Answer: Description for Correct answer:
Let the price of each book is Rs.x and the number of books is y.
xy = 80 ... (1)
And (y + 4)(x - 1) = 80
= > xy - y + 4x - 4 = 80
80 - y + 4x = 4 + 80
4x - y = 4
y = 4(x - 1)
From equation (1)
4(x -1)x = 80
= > \( x^2 - x -20 = 0 \)
= > \( x^2 - 5x + 4x -20 = 0 \)
= > (x - 5)(x + 4) = 0
x = 5.. (x is not equal to -4)
Hence the price of each book is Rs. 5.
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