You will have to decide WHEN you made it or lost it. You can then calculate equivalent values in the separate currencies.
I apologise if this is posted in the wrong place.
Here's the problem:
Bought a property in Cyprus in 2006 when Cyprus had the Cyprus pound. Took the mortgage out in Swiss francs. Now I'm selling it in Euros and will be changing the euros back to GBP.
How the heck do I work out how much I've made (lost)?