What is IMA?

I'm given a picture of a pulley system and I was told to find the IMA of that pulley system.
Buuut i don't know how to find the IMA, there are no numbers given in the picture.
So what is IMA and how do I find it?

3 answers

I found Ideal Mechanical Advantage.
http://en.wikipedia.org/wiki/Mechanical_advantage
Thank you, to both of you. (: