#### Answer

$x\geq3$

#### Work Step by Step

In order to create the given number line, we solve for the given variable. Then, we shade the number line. If the number line is less than a given number, we shade to the left of that number, but if x is greater than the given number, then we shade to the right of that number. If there is an underline under the inequality symbol, then we shade the circle at the endpoint to signify that the given point is a solution to the inequality. If the point is not included, then we do not color the circle in. We flip the inequality sign because we are dividing by a negative.
$-7x\leq-21$
$x\geq3$
Recall, when we divide or multiply by a negative, we flip the inequality symbol.