Here is your equation:

In the question, you are given that m is equal to -8. Substitute m with -8. Here is your new equation:

Now, all you need to do is divide. Remember:
MULTIPLYING
- Positive(+) times negative(-) is equal to negative
- Positive(+) times positive(+) is equal to positive
- Negative(-) times negative(-) is equal to positive
- Negative(-) times positive(+) is equal to negative
DIVIDING
- Positive(+) divided by positive(+) is equal to positive
- Positive(+) divided by negative(-) is equal to negative
- Negative(-) divided by positive(+) is equal to negative
- Negative(-) divided by negative(-0 is equal to positive
In this question, you're dividing a negative number by a positive. That means the answer will be negative. Divide:

Your answer is -4.
If you have any questions, feel free to ask in the comments! :)