Example

Find an equation of the horizontal line that passes through the $y$-intercept of the line described by $y=5x-8$.

Solution

The given line is in slope-intercept form. We can directly read its $y$-intercept. It is $(0,-8)$. So now we must find an equation of the horizontal line passing through $(0,-8)$.

Every horizontal line can be written in the form $y=b$, where $b$ is a constant. In this case $b=-8$, and our equation is