Both of these numbers are negative, so for the sake of ease, let's multiply both by -1 to make the equation 8 / 2/5.
First, let's make 8 into a fraction.
8/1 / 2/5
Now, use "keep, change, flip."
Keep 8/1...
Change the division sign into a multiplication sign...
8/1 * 2/5
And flip 2/5 into 5/2 (the reciprocal).
Now we have 8/1 * 5/2.
What we'll do is multiply the numerators together to find the solution's numerator and the denominators to find the solution's denominator.
8*5 = 40
1*2 = 2
We get 40/2. This can be simplified into 20/1, or just plain 20.
In conclusion, -8 / -2/5 = 20.