This math problem is really a difficult problem.

This math problem is too obscure, I can't understand it.

This math problem is very dense.

What is this, that box?

Learning about the culture of Southeast Asia is very interesting.

My house is located in the southeast of the city.

He neatly adjusted the knot of his tie.

He is pulling the strings behind the scenes, controlling everything.

It's difficult to find the clue to this problem.

She was winding the thread around the spool.