$38$

Select the function that has a well$-$defined inverse.

$f$:$ZZ$

$f(x)=x+4$

$f$:$ZZ$

$f(x)=2x-5$

$f$:$Z{Z}^{+}$

$f(x)=|x|$

$f$:$ZZ$

$f(x)=|$~$\frac{x}{2}$~$|$