Question

cost of 3 pencil and 1 eraser is 7 rupees and cost of 1 pencil and 2 eraser is 4 rupees.so what is the cost of pencil and eraser.

Answer 1

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Answer 2

Answer :

The cost of 1 pencil = 2 rupees

The cost of 1 eraser = 1 rupees

Explaination :

Let ,

The cost of 1 pencil = x rupees

The cost of 1 eraser = y rupees

According to the question ,

3x + y = 7 ------------ eq (i)

x + 2y = 4 ------------ eq (ii)

Multiply eq (i) by 1 and eq (ii) by 3

we get ,

3x + y = 7 ------------ eq (iii)

3x + 6y = 12 ---------- eq (iv)

Subtract eq (iii) from eq (iv)

➡3x + 6y - ( 3x + 1y ) = 12 - 7

➡3x + 6y - 3x - 1y = 5

➡5y = 5

➡y = 1

Put the value of y = 1 in eq (i)

➡3x + 1 = 7

➡3x = 6

➡x = 2

Hence , the cost pencil and eraser is 2 and 1 ruppes .