Make a little circle on the 15 on the number line.
Since the inequality symbol includes "or equal" fill in the little circle. Any time you don't have "or equal" as in < or >, leave the circle open.
Since the inequality is "less than" make a heavy line, starting at the little filled in circle, all the way to the left end of your number line. Had it been "greater than" the heavy line would have gone to the right.
