The problem asks us to find the equation of a line given its slope and y-intercept. The slope is given as $4$ and the y-intercept is given as $(0, 0)$. We need to write the equation in slope-intercept form.

1. Problem Description

The problem asks us to find the equation of a line given its slope and y-intercept. The slope is given as $4$ and the y-intercept is given as $(0, 0)$. We need to write the equation in slope-intercept form.

2. Solution Steps

The slope-intercept form of a linear equation is given by:

$y = mx + b$

where $m$ is the slope and $b$ is the y-intercept.

In this problem, we are given that the slope $m = 4$ and the y-intercept is $(0, 0)$. This means that $b = 0$.

Substituting these values into the slope-intercept form, we get:

$y = 4x + 0$

$y = 4x$

3. Final Answer

$y = 4x$