Cost of a notebook is twice cost of a pen. Write a linear equation in two variables to represent thi

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4. Linear Equations in Two Variables

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The cost of a notebook is twice the cost of a pen. Write a linear equation in two variables to represent this statement.

(Take the cost of a notebook to be $\rm {Rs.}$ $x$ and that of a pen to be $\rm {Rs.}$ $y$).

Option A

Option B

Option C

Option D

Solution

Let the cost of a notebook $=$ Rs. $x$

The cost of a pen $=$ Rs. $y$

According to the condition, we have

$[$ cost of a notebook $]=2 \times[$ cost of a pen $]$

$[ x ]=2 \times[ y ]$

$x=2y$

or $x-2 y=0$

Thus, the required linear equation is $x-2 y=0$.

Standard 9

Mathematics

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