Question

The total cost of 7 books and 8 pens is 80 ruppes and the total cost of 8 books and 6 pens is 78 ruppess find the cost of 12 books and 3 pens?​

Answer 1

Answer:

Let cost of book be x & cost of pen be y

⇒8x+5y=420;⇒5x+8y=321

Adding = 13x+13y=741;x+y=57 ____ (1)

Subtracting = 3x−3y=99;x−y=33

substituting x=y+33 in equation (1) we get :

y+33+y=57⇒2y=24⇒y=12

so x=12+33=45

cost of 1 book & 2 pens = 45+2(12)= 45+24

= 69 Rs

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