[ladyvoid]

Calculate the sodium ion concentration when 71.9 mL of 4.3 M sodium carbonate is added to 33.7 mL of 2.5 M sodium bicarbonate.
 
I tried to work this problem out, but I kept getting the wrong answer. Could somebody walk me through the steps on how to solve this? It's very much appreciated.

[DevaDevil]

can you show your attempt? we may then be able to help you by pointing out where the calculation goes wrong