Q. 185.0( 1 Vote )

# The total cost of the 5 books and 7 pens is ₹79 while the total cost of 7 books and 5 pens is ₹ 77. Find the total cost of 1 book and 2 pens.

Answer :

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

5x + 7y = 79 …equation (i)

7x + 5y = 77 …equation (ii)

Multiplying equation (i) by 7 and multiplying equation (ii) by 5 we get

35x + 49y = 553

35x + 25y = 385

Subtracting the above two equations we get

24y = 168

⇒ y = 7

5x + 49 = 79

⇒ 5x = 30

⇒ x = 6

Cost of 1 book and 2 pen = (6 + 14) = Rs. 20

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PREVIOUSThe total cost of the 5 books and 7 pens is ₹79 while the total cost of 7 books and 5 pens is ₹ 77. Find the total cost of 1 book and 2 pens.NEXTA two - digit number is such that when it is multiplied by 9 then it will become double of number formed by interchanging the digits of the original number. If the difference of both the digits of the number is 7 then find the number.

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