Answer:
Hence, the required relationship is: 
Step-by-step explanation:
We have been given two functions:

And 
We can see that angle is same that is sin 5x
So, for a relationship between both the functions we need to relate the amplitude that is
(1)
Where, a is amplitude.
If we compare two functions with (1) amplitude of f(x) is -1/2 and g(x) is 4
So, if we multiply -8 with f(x) that is:



Hence, the required relationship is: 