Answer:
y=8
Explanation:
In functions, you should know that f(x)=y. In this problem, y is replaced by 4(0.5)^-1. So all you need to do is solve what 4(0.5)^-1 is, which is 8. This means that f(x)=8, but y is also equal to f(x). The answer is then y=8.
Hope you understand and that this helps with your question! :)