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.)
x − 2y = 0
Let notebook cost be \(x\) and pen cost be \(y\). The statement says notebook cost is twice pen cost, so \(x = 2y\).
Move all terms to one side to match \(ax + by + c = 0\): \(x - 2y = 0\).
This is linear because the highest power of \(x\) and \(y\) is 1.