Question

The cost of a notebook is twice the cost of a pen . write a linear equation in two variable

Answer 1

Hey !

Cost of pen = x
Cost of notebook = y 

a.t.q.,

2x = y 

2x - y = 0

Answer 2

Let the cost of a notebook be x and that of a pen be y.

According to question,

The cost of a notebook is twice the cost of a pen

Or, x = 2y

Or, x - 2y = 0.