Norton's Equivalent - What do you do in this situation?

[zanner]

Hi,

So I have managed to get part of the way through solving a circuit that is being made into a Norton's equivalent circuit. But now I'm stuck on the Isc part. I know I have to use the current divider rule, but I'm not sure how to use it in this situation.

Here's a diagram:

 

[NascentOxygen]

What is your equation for current through R₂ in the circuit you have drawn?

Hint: it is always a good idea to redraw schematics while you mull over what approach to take; perhaps redraw multiple ways. Redrawing a circuit in a simpler/neater/alternative way engages the brain in considering different ways of viewing the connections, and often brings sudden insight.