# Ex.4.1 Q1 Linear Equations in Two Variables Solution - NCERT Maths Class 9

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## Question

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 $$₹\, x$$  and that of a pen to be $$₹\, y.$$)

Video Solution
Linear Equations In Two Variables
Ex 4.1 | Question 1

## Text Solution

#### Steps:

• Let the cost of one notebook be $$₹\, x$$
• Let the cost of one pen be $$₹\, y$$

Given: Cost of notebook is twice the cost of pen.

Therefore, we can write the required linear equation in two variables considering the given information as,

Cost of notebook $$= 2 \times$$ Cost of pen

$$\Rightarrow x = 2 y$$

Since any linear equation of two variables is expressed as:

$$a x + b y + c = 0,$$

$$\therefore \,x - 2 y = 0$$ is the required linear equation in two variables which represents the given information.

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