Question

The total cost of 8 books and 5 pens is 420 rupees and the total cost of 5 books and 8 pens is 321 rupees.find the cost of 1 book and 2 pens?

Answer 1

Answer:

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Answer 2

The cost of 1 book and 2 pens is Rs 69.

Step-by-step explanation:

Let the cost of 1 book is Rs x and that of one pen is Rs y.

Hence, we have below two equations on the basis of given directions

$8x+5y=420...(i)\\\\5x+8y=321...(ii)$

Multiply (i) by 5 and (ii) by -8 and then add

$40x+25y-40x-64y=2100-2568\\\\-39y=-468$

Divide both sides by -39

$y=\frac{-468}{-39}\\\\y=12$

Substituting the value of y in (i)

$8x+5\cdot12=420\\\\8x+60=420\\\\8x=360\\\\x=45$

Now, find the value of the expression

x + 2y

= 45 + 2× 12

= 45 + 24

= 69

Hence, the cost of 1 book and 2 pens is Rs 69.

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Ram and Mohan are brothers.rams present age is three years more than twice the present age of Mohan .if the sum of their present age is 27. find their ages

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