Help pls

1 .Function  is defined as follows:

$\[g(x) = \left\{ \begin{array}{cl} 5x^2 & \text{if } x \le -3, \\ 21+x& \text{if }-3 < x \le 10, \\ 2-\sqrt{x}& \text{if }x > 10. \end{array}\right.\]$

This function has an inverse.

What is $g^{-1}(-7)$

2. Function C is defined on positive integers as follows:

$\[C(n) = \begin{cases} \dfrac n 2 & \text{if $n$ is even}, \\ 3n+1 & \text{if $n$ is odd}. \end{cases}\]$

Find the smallest positive integer m such that $C^m(9) = 1$

2b. Find all n such that $C^3(n) = 16$