Question

If seven books and 5 pens cost Rs 410, whereas five books and seven pens cost Rs.334 then the cost of three books and four pens would be a) Rs.135 b) Rs.145 c) Rs.255 d) Rs.198​

Answer 1

Answer:

d) is correct answer

Step-by-step explanation:

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Answer 2

SOLUTION

TO CHOOSE THE CORRECT OPTION

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

a) Rs. 135

b) Rs. 145

c) Rs. 255

d) Rs. 198

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

FINAL ANSWER

Hence the correct option is d) Rs. 198

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