The total cost of 6 books and 7 pens is 79 rupees and the total cost of 7 books and 5 pens is 77 rupeess. Find the cost of 1 book and 2 pens.

#### Solution

**Disclaimer:** There is an error in the given question. Instead of 7 books and 5 pens there should be 7 books and 6 pens.

Let the cost of 1 book be x and the cost of 1 pen be y.

The total cost of 6 books and 7 pens is 79 rupees.

6x + 7y = 79 .......(I)

Total cost of 7 books and 6 pens is 77 rupeess.

7x + 6y = 77 .........(II)

Adding (I) and (II)

13x + 13y = 156

⇒ x + y = 12 ..........(III)

Subtracting (II) from (I)

- x + y = 2 ..........(IV)

Adding (III) and (IV)

2y =14

⇒ y = 7

⇒ x = 5

So, the cost of one book is 5

And one pen is 7

So, Cost of 1 book and 2 pens is

x + 2y = 5 + 2(7) = 5 + 14 = Rs. 19