First example:
Subtract the 8n on both sides to get the variable on one side of the equation. Do the same for the regular numbers. Then divide by -3.
This should be your final answer.
Second Example:
Do the same thing as explained in Example 1. Here's some work to help guide you.
That should be your final answer here.
Third Example:
Hope this helps and its understandable! Let me know if you still don't understand.