Find an equation to transform $\{1, 2, 3, 4, 5,6, 7, 8\}$ to $\{8,7,6,5,4,3,2,1\}$ Is there a way to transform $\{1, 2, 3, 4, 5,6, 7, 8\}$ to $\{8,7,6,5,4,3,2,1\}$ by applying a single function?
That is, transform $1$ to $8$, $2$ to $7$, $3$ to $6$ etc.

$f(x) = 9 - x$
$f(1) = 9 - 1= 8$
$f(3) = 9 - 3 = 6$
etc.
