The problem has been solved satisfactorily at last.

问题终于完满解决。

《新英汉大辞典》

But now that problem has been solved.

但是现在这个问题已经得到解决。

youdao

The problem has been solved quite simply.

这个问题很简单就解决了。

youdao

Now, the FAA's Nick Sabatini says that problem has been solved as well.

NPR: For Air Travelers, More Safety and More Problems

Fast forward to six years later to Duke grad student Nathan Landy, and it looks like that problem has been solved.

FORBES: Duke Researchers Perfect The Original Invisibility Cloak

We think that problem has been solved.

WSJ: Is NFC Finally Becoming Mobile's Next Big Thing?