Question

cost of some books is rupees 60 cost of every book is same if the bookseller decreases the cost of book by rupees 1 then one gets five books more for some same amount what is the cost of each book and how many books are purchased​

Answer 1

Answer:

15 books Rs 4 Each

Step-by-step explanation:

Let say number of books whose cost is Rs 60 = x

So cost of each book = 60/x  Rs

Cost decreased by rs 1 means

=> Decreased cost = (60/x) - 1  Rs

Number of books now = x + 5

{(60/x) - 1 } × (x + 5 ) = 60

multiplying by x on both sides

(60 - x )(x+5) = 60x

-x² + 60x -5x + 300 = 60x

-x² - 5x + 300 = 0

x² + 5x - 300 = 0

x² + 20x - 15x - 300 = 0

x (x+20) - 15(x+20) = 0

(x-15)(x+20) = 0

x = 15   as x = -20 not possible as books can not be negative

Number of books purchased = 15

cost of each book = 60/15 = 4 Rs