I also got 10.

And since some already did so before me, I'm not gonna put mine into spoiler-tags either. Good thing I didn't scroll down before solving it.
On a sidenote, I have no clue what linkedin is. Might have read the name somewhere before (once or twice), but that's all I've ever heard of it xD.
Edit: Was nice to solve a little math-puzzle after being out of school for that long already. Took me only like 2 minutes or so too. Gosh I remember the good old times...