I don't know what the ___(solve) to her trouble is.

I don't know what the ___(solve) to her trouble is.
I don't know what the ___(solve) to her trouble is.

I don't know what the ___(solve) to her trouble is.
I don't know what the solution to her trouble is.
我不知道她的问题(麻烦)的解决方法.

solving

希望能帮上你，谢谢！