Energy lever question

This was posted and answered yesterday....see previous post.

Can you link it? I can't find it.

http://web2.0calc.com/questions/when-a-15-newton-force-is-applied-to-on-end-of-a-lever-100-cm-long-a-60-newton-weight-is-attached-to-the-opposit-end-is-lifted-what-is-the-length-of-the