Question

find the cost....????? plz full sum plz

Answer 1

Answer:

15

Step-by-step explanation:

Given, cost of some books = 60.

Let the cost of each book be 'x'.

So, the number of books that can be purchased == (60/x).

Now,

Given that bookseller decreases the cost of the book by 1.

Now, the cost of each book be 'x - 1'

So, the number of books that can be purchased = (60/x - 1).

According to the given condition,

⇒ (60/x - 1) = (60/x) + 5

⇒ 60x = 60(x - 1) + 5x(x - 1)

⇒ 60x = 60x - 60 + 5x² - 5

⇒ 5x² - 5x - 60 = 0

⇒ x² - x - 12 = 0

⇒ x² - 4x + 3x - 12 = 0

⇒ x(x - 4) + 3(x - 4) = 0

⇒ (x - 4)(x + 3) = 0

⇒ x = 4, -3{Cost cannot be negative}

⇒ x = 4.

Then:

⇒ 60/x

⇒ 60/4

⇒ 15.

Therefore, number of books that can be purchased = 15.

Hope it helps!

Answer 2

Step-by-step explanation:

Let cost of x books be 60

One book cost = 60/x

According to ques,

60/x - 60/(x + 5)  = 1

60[x+5 - x]=x^2 + 5x

300 = x^2 + 5x

x^2 + 5x - 300 = 0

x^2 + 20x - 15x - 300 = 0

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

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

-> x=15 (since cost cant be -20)