Excel Formula Help

[Desmo]

Hey hey

Need some help with this formula that my dumb excel brain can't get to work.



This is a very simplified chart, but what I need to do is cross reference some of the information when I fill in the fields.
What I want to do is fill in Amount (B9 Yellow box) and Size (B10 Orange box) which then cross references the information and gives me the total.

So, Amount = 2000, Size = A4 Double, Total should = 3


If I can get this working, I can add in other charts using the same formula and hopefully make our quoting system a lot easier and quicker