Lets get started!
In this case, it's quite simple.
Multiply both numerators by each other
The number are the top numbers of the fraction
-5 x 2 = -10
Now we multiply the denominators, the bottom numbers
8 x 3 = 24
Your final answer is -10/24
If you want to simplify (meaning to make smaller or easier to look at), divide the top and bottom numbers by 2
Your simplified answer is -5/12
Hope I helped :)