Question

If seven books and 5 pens cost Rs 410, whereas five books and seven pens cost Rs.334 then the cost ofthree books and four pens would be​

Answer 1

Hopefully it will help you!!

Answer 2

SOLUTION

GIVEN

Seven books and 5 pens cost Rs 410

Five books and seven pens cost Rs.334

TO DETERMINE

The cost of three books and four pens

EVALUATION

Let cost of one book = Rs x and cost of one pen = Rs y

So by condition 1

7x + 5y = 410 - - - - - - - (1)

By condition 2

5x + 7y = 334 - - - - - - - (2)

Multiplying both sides of Equation 1 by 7 we get

49x + 35y = 2870 - - - - - - (3)

Multiplying both sides of Equation 2 by 5 we get

25x + 35y = 1670 - - - - - - (4)

Equation 3 - Equation 4 gives

24x = 1200

⇒ x = 50

From Equation 1 we get

5y = 410 - 7x

⇒ 5y = 410 - ( 7 × 50 )

⇒ 5y = 410 - 350

⇒ 5y = 60

⇒ y = 12

∴ Cost of one book = Rs 50 and cost of one pen = Rs 12

Hence the required cost of three books and four pens

= Rs 3x + Rs 4y

= Rs 150 + Rs 48

= Rs 198

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