How to lookup criteria in two columns

Hi

thanks for getting back to me. I think my brain may be a little frazzled but I could not get it to work.

Also I may not have explained what I was trying to do very clearly. Here is a very simplified extraction from the sheets I am using

spreadsheet 1
PO expected cost Result
14373 26.37 [actual cost should appear here]
14365 40.99 [actual cost should appear here]
14365 24.5 [actual cost should appear here]


spreadsheet 2
PO invoice no desciption actual cost
14365 71337 40275 27221 Goods 24.08
14365 71312 40274 27220 Goods 40.99
14373 E45040 40274 27323 gifts 26.37

I basically want to get the actual cost from sheet 2 into sheet 1 but having checked that it corresponds with col a and b in sheet 1.

Also do they have to be formatted as text or as numbers - doesnt A1&A2 usually concatenate numbers and add them together? In which case here it will bring back the wrong result. I need to leave everything as numbers for other formulea in the spreadsheet to work.

Any ideas would be really appreciated.