I am old, so I like to use paper & pencil
It's a simple linear equation in 'n'. There's only one number that 'n' can be
that will make the equation a true statement. That number is called the
'solution' to the equation. Here's one way to find it:
You said that <u> -7n - 4 = 24</u>
Add 4 to each side: -7n = 28
Multiply each side by -1 : 7n = -28
Divide each side by 7 : <em>n = -4</em>
Homework is the only way for most people to learn stuff.
After having done this on paper:

We want to isolate the variable, and the first step is to subtract the 8.

Since the <em>n</em> is being multiplied by 3, and that = 8, we can multiply both sides by 3.
<em>n</em> = 24
Let me know if this helped you understand better.
Also, you can check this by substituting in 24 for <em>n</em>.
18.8333333333is the answer