Find the equation of the line which passes though (0, 0) with slope m.

We know that the equation of the line passing through point $\left(x_{0}, y_{0}\right)$, whose slope is $m$, is $\left(y-y_{0}\right)=m\left(x-x_{0}\right)$.

Thus, the equation of the line passing through point (0, 0), whose slope is m,is

(y – 0) = m(x – 0)

i.e., y = mx