Need help with conditional formatting as a result of selections from a drop down list

Hello,

I am trying to programme a worksheet such that selections made from two drop down lists would result in a cell changing colour.

There are 2 categories of criteria, Probability vs Impact

Each category is represented in a column, and has 5 variables in a drop down lists

There are 25 different iterations possible, each interation should result in a different colour in the 3rd column (either green, yellow, blue or red)

For instance

One set of variables is, say A,B,C,D,E and the second set F,G,H,I,J

If one chooses a combination of variable A and G = colour red
or variable A and I = colour green
or B and G = colour yellow

I managed to program this with multiplying numbers so X x Y = Z and Z yields the colour

But since my variables are actual words and therefore text-based, I'm not sure how to go about programming this.

Does anyone have any suggestios?

I am working with Excel 2010.

Thank you