Question

solve using elimination methods


5 books and 7 pens together cost Rs 79, whereas 7 books and 5 pens together cost Rs 77. Find the cost of 1 book and 2 pens


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Answer 1

Answer:

Let the cost of 1 book =x

And the cost of 1 pen =y

⇒5x+7y=79

⇒7x+5y=77

Equation (1) × 7 : 35x+49y=79×7

Equation (2) × 5 : 35x+25y=77×5

Subtract two equations ;

⇒24y=168

⇒y=7

⇒x=6

Total cost of 1 book and 2 pens =x+2y=6+14=20