# 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.