5 pencils and 7 pens together cost Rs 195 while 7 pencils and 5 pens t

1.	5 pencils and 7 pens together cost Rs 195 while 7 pencils and 5 pens together cost Rs 153. Find the cost of each one of the pencil and pen.
Answer» Let the cost of each pencil be Rs. x and that of each pen be Rs. y. Then, we have: 5x + 7y = 195 ………(i) 7x + 5y = 153 ………(ii) Adding (i) and (ii), we get: 12x + 12y = 348 ⇒ 12(x + y) = 348 ⇒ x + y = 29 ………(iii) Subtracting (i) from (ii), we get: 2x – 2y = –42 ⇒ 2(x – y) = –42 ⇒ x – y = –21 ………(iv) On adding (iii) and (iv), we get: 4 + y = 29 ⇒ y = (29 – 4) = 25 Hence, the cost of each pencil is Rs. 4 and the cost of each pen is Rs. 25.

5 pencils and 7 pens together cost Rs 195 while 7 pencils and 5 pens together cost Rs 153. Find the cost of each one of the pencil and pen.

Answer»

Let the cost of each pencil be Rs. x and that of each pen be Rs. y.

Then, we have:

5x + 7y = 195 ………(i)

7x + 5y = 153 ………(ii)

Adding (i) and (ii), we get:

12x + 12y = 348

⇒ 12(x + y) = 348

⇒ x + y = 29 ………(iii)

Subtracting (i) from (ii), we get:

2x – 2y = –42

⇒ 2(x – y) = –42

⇒ x – y = –21 ………(iv)

On adding (iii) and (iv), we get:

4 + y = 29 ⇒ y = (29 – 4) = 25

Hence, the cost of each pencil is Rs. 4 and the cost of each pen is Rs. 25.