I want to translate this into German. **I would have told it to you if I had known it**.. 

I would write
... **Ich hätte es ihnen gesagt, wenn ich es gewusst hatte"**

'hatte' means 'had' in English so I thought that the sentence should have continued with 'hatte'

But the correct answer was written with 'hätte' ".... **wenn ich es gewusst hätte**"

But I don't want to say "....**if I would have known it**."

I hope you understand.