Leaving aside the sign or direction of something like 5 - 3, which perhaps would need to include an arrowhead, as well as other possible graphical conventions I am not familiar with,
Which one of the graphical options below (A or B) would make more sense to express 5 - 3:
?
I would say that A makes more sense, because you are "leaving 3 behind" and moving on along the real line until you reach 5. So 5 should be included, but 3 should be excluded.
As detailed in the comments (sorry I think I initially misinterpreted what you were trying to say as subtraction not an interval), if you are indeed talking about interval notation (http://www.coolmath.com/algebra/07-solving-inequalities/03-interval-notation-02), then A is the correct answer, as $\circ$ indicates an “open” interval (ie strictly greater or less then). A line indicates a “closed” interval (greater than/less than or equal to).
In non-diagrammatic notation, the interval you’re trying to express would be written is either $(3,5]$ or $]3,5]$, both of which are equivalent ways of saying
$$\{ x \mid 3 < x \leqslant 5, x \in \Bbb{R} \}.$$