I don't get the difference between 할 수 있다 and 할 수 있어. (다 and 어). I want to write ‘I can do it’. I want to do a tattoo but I don't know which one is proper one?
-다 and -어 have lots of cases.
-다 is formal one -어 is informal one.
When u talking with people, it is more natural to speak '나는 할 수 있어'. However, When u write for letters or books, it would be more natural to speak '나는 할 수 있다'
나는 할 수 있다 (-다) => It describes the states, facts of some situations. 나는 할 수 있어 (-어) => It is more like colloquial style.