Answer
$3.5\leq r$
Work Step by Step
$9\leq-12+6r$ $\longrightarrow$ add 12 to both sides
$9+12\leq-12+6r+12$ $\longrightarrow$ simplify
$21\leq6r$ $\longrightarrow$ divide both sides by 6
$21\div6\leq6r\div6$ $\longrightarrow$ simplify
$3.5\leq r$
Check the endpoint.
$9=-12+6(3.5)$
$9=-12+21$
$9=9\checkmark$
Check the inequality.
$9\leq-12+6(4)$
$9\leq-12+24$
$9\leq12\checkmark$
