Question

The total cost of 6 books & 7 pens is 79 rupees and total cost of 7 books 4 & 5 pens is 77 rupees, find cost of 1 book & 2 pens.​

Answer 1

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Let the cost of 1 book

pen be y.

The total cost of 6 books and 7 pens is 79

rupees.

6x + 7y = 79

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

7x + y = 77

Adding (1) and (1)

13x + 13y 156

X + y 12 Subtracting (X) from (1)

-x + y = 2

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 =

.(1)

(III)

...(\V)

Answer 2

Let the cost of 1 book

pen be y.

The total cost of 6 books and 7 pens is 79

rupees.

6x + 7y = 79

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

7x + y = 77

Adding (1) and (1)

13x + 13y 156

X + y 12 Subtracting (X) from (1)

-x + y = 2

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 =

.(1)

(III)

...(\V)