How is the function f(x)=-1/2sin5x related to the function g(x)=4sin5x?

From the question we have that f(x) = -1/2 sin 5x and g(x) = 4 sin5x
Let's try to calculate -8f(x)
- 8f(x) = -8 (-1/2 sin 5x)
This becomes 4sin 5x
Since the function g(x) is -8 times f(x)
Hence g(x) = -8f(x)