#### Answer

$12\leq f$

#### Work Step by Step

$8\leq f-4$ : add 4 to both sides
$8+4\leq f-4+4$ : simplify
$12\leq f$
Verify that 12 is a solution at the endpoint.
$8\overset?= 12-4$
$8=8\checkmark$
Verify that a number greater than 12 is a solution.
$8\overset?\leq14-4$
$8\leq10\checkmark$