Question

The cost of 4 pens and a pencil boxes is Rs 100
Three times the cost of a pen is Rs15 more than the cost
of a pencil box find the
cost of a pen and a pencil box respectively​

Answer 1

Answer:

Let the cost of a pen Rs x and the cost of a pencil box be Rs. Y. Hence, the cost of a pen and a pencil box are Rs 10 and Rs 15, respectively.

Step-by-step explanation:

Answer 2

Answer:

Solution :-

Let the cost of a pen be Rs 'x' and the cost of a pencil box be Rs. 'y'

As, the cost of 4 pens and 4 pencil boxes is Rs. 100

So, 4x + 4y = 100 ....(1)

And, three times the cost of a pen is Rs. 15 more than the cost of a pencil box.

So, 3x = y + 15

⇒ 3x - y = 15 ....(2)

Now multiplying the equation (1) by 3 and equation (2) by 4, we get

⇒ (4x + 4y = 100)*(3) = 12x + 12y = 300 ...(3)

⇒ (3x - y = 15)*(4) = 12x - 4y = 60 ....(4)

Now, subtracting (4) from (3)

12x + 12y = 300

12x -  4y   = 60

-     +           -

_________________

        16y = 240

_________________

⇒ 16y = 240

⇒ y = 240/16

⇒ y = 15

Now, substituting the value of y = 15 in (2)

⇒ 3x - y = 15

⇒ 3x - 15 = 15

⇒ 3x = 15 + 15

⇒ 3x = 30

⇒ x = 30/3

⇒ x = 10

So, the cost of a pen is Rs. 10 and the cost of a pencil box is Rs. 15..

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