この問題を解くの

solving this problem

→ この
phrase Rare #40,866
solving this problem The の turns the verb phrase into a noun-like phrase; depending on the sentence, it can also be translated as “to solve this problem.”
JA: この問題を解くのは時間がかかる。
EN: Solving this problem takes time.

私にはこの問題を解くのは難しい。

It's difficult for me to solve this problem.

この問題を解くのを手伝っていただけませんか?

Could you help me solve this problem?

この問題を解くの、私には難しいな。

This problem is hard for me to solve.

この問題を解くのは難しい。

This problem is difficult to solve.