Here are two boy's cars.
But.
Here are two solutions key points.
Why in first example is "'s" used and in second one it's not?
I checked with LanguageTool and GoogleTranslate. I want to explain to key point for the solution of a problem, then used a tools and get confused.
https://www.britannica.com/dictionary/eb/qa/How-to-Make-Possessives-in-English
Or is this correct?
Here are two solution's key points.