jacksparrow

Always find the implied cross rate and compare it with the actual one - for example, you have 3 rates:

x/y - y/z - z/x

divided or multiply two of them and you will get an IMPLIED rate for the third one - if the implied rate is different than actual one, then you will have arbitrage profit ..

Use chain rule after that:

start with x --> y --> z --> x

if you end up with a loss, reverse,

x --> z --> y --> x

you will end up with a profit

This is of course assuming that we are dealing with the average of bid-ask .. if bid-ask quotes are given, you need to take that into consideration