A solid dot on a number line graph indicates that the given number should be included as a possible solution, whereas an open dot indicates that the given number cannot be a solution. For example, if you graph x > 7, you place an open dot at 7.
the number can be greater than or equal to 3 so it means that includes 3 so closed circle on 3 and then it points right towards the bigger numbers because it can be greater than 3