# 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).

**Solution:**

- Let the cost of one notebook be ₹ x
- Let the cost of one pen be ₹ y

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

Cost of notebook = 2 × Cost of pen

⇒ x = 2y

Since any linear equation in two variables is expressed as: ax + by + c = 0,

∴ x - 2y = 0 is the required linear equation in two variables which represents the given information.

**Video Solution:**

## 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).

### NCERT Solutions Class 9 Maths - Chapter 4 Exercise 4.1 Question 1:

**Summary:**

If the cost of a notebook is twice the cost of a pen, then a linear equation in two variables to represent this statement is x - 2y = 0.