Question

Fourpens and three erasers cost Rs.17. Four erasers and 3 pens cost Rs.18. Find the total cost of a pen and a eraser.

Answer 1

1x+2y+4z=22
5x+4y+2z=32
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6x+6y+6z=54
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6 pencil 6pens 6 eraser cost is =54
So 3 pencil 3pens 3 eraser =54/2=27

Answer 2

Let the cost of 1 pen be x and 1 eraser be y.

ATQ

4x+3y = ₹17

3x+4y = ₹18

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7x+7y = ₹35

7(x+y) = ₹35

x+y = ₹5

x = ₹5-y

Putting the above value of x in any of the two equations.

4(5-y)+3y = ₹17

20-4y+3y = 17

-y = -3

y = ₹3

x = ₹5-₹3 = ₹2

Hence, the cost of 1 pen = ₹2 and cost of 1 eraser = ₹3