You know the line passes through $(-3, 7)$ and has slope $4$. Try substituting $x = -3$, $y = 7$, and $m = 4$ into $y = mx + b$.

After substituting, you will get a simple equation involving only $b$. Rearrange this equation to isolate $b$ on one side.

In a Desmos expression line, type 7 - 4(-3) and press Enter. The value Desmos outputs is the value of $b$ in the equation $y = 4x + b$ for a line passing through $(-3, 7)$.

A line with slope $m$ and $y$-intercept $b$ can be written as $y = mx + b$.

Here, the slope is $4$, so the line has the form

where $b$ is the unknown $y$-intercept we need to find.

The line passes through $(-3, 7)$, which means when $x = -3$, $y = 7$.

Substitute $x = -3$ and $y = 7$ into $y = 4x + b$:

Now simplify $4(-3)$ to get:

We now solve $7 = -12 + b$ for $b$.

Add $12$ to both sides:

19 = b