This is the 3871st most frequent Korean word.
어렵지
"어렵지" means "isn't it difficult?" or "it's difficult, isn't it?"
In this sentence, "어렵지" is used to describe the level of difficulty of the problem.
이 문제는 정말 어렵지.
This problem is really difficult.
Here, "어렵지" implies speculation about the difficulty of the situation.
그래서 이길기가 어렵지 않을까 생각해.
Thus, I think winning would not be easy.
In this case, "어렵지" contrasts the difficulty before and after an action, emphasizing the tasks becoming less hard.