NCERT Exercise 4.1 Q1 - Linear Equations in Two Variables
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.)
Answer: x = 2y, or equivalently x − 2y = 0.
Full step-by-step NCERT solution with diagrams on Something by Zero.