Exp bar as current/max

So i want to make a system where you kill a mob and you get 1 "exp" and when you get 4 you level up (its for my skill system) but i want to show it like a progress bar with numbers like i have killed 4 mob but i need a total of 8 like (4/8) or if ive killed 1 (1/8) i can someone show me how to please 

(pref with images of procedures too)