Question

Five books and 7 pens together cost Rs 79 7 books and 5 pens together cost
rupees 77 find the cost of two books and one pen

Answer 1

hy friend                            

                 here is your answer

                                                                                                                                 

∴ Let the cost price of 2 book be Rs. 'x'

∴ the cost price of 1 pen be Rs. 'y'

            according to the question.              

⇒ 5x + 7y = 79  ...........(1)

⇒ 7x + 5y = 77  ...........(2)

Multiplying the equation....

      (1) by 7 and equation

       (2) by 5, we get

→ 35x + 49y = 553.......(3)

→ 35x + 25y = 385.......(4)

 Now subtracting ...(4) from (3)

       ⇒ 24y = 168

       ⇒ y = 168/24

       ⇒ y = 7

Substituting value of y = 7 in (1)---

  ⇒ 5x + 7*7 = 79

  ⇒ 5x = 79 - 49

  ⇒ 5x = 30

   ⇒ x = 6

→ cost of 2 book is Rs. 12  and cost of 1 pen is Rs. 7 

→ cost of 1 book and 2 pens =  (6*2) + 7

= 12 + 7

= Rs.19

Answer.

                                                                                                                               

thankyou

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Answer 2

that was very big though for 5 points
mark me as brainliest