Since it's H^-1(x), than just look at the H(x)=x section and do the following:
1) Substitute the x in the equation for the x from the H^-1(x) -
H(x)= (x)
2) Next take the x out of the parentheses cause there's nothing to multiply it to:
H(x)= x
3) x is your answer cause there's nothing else to do
Answer: x
outro; live