3 drop-down lists and lookup value

I have 3 drop down lists shaded in green. I want to choose a Hydrologic Soil Group from a drop-down list. I want to choose a Cover Type from a drop-down list. Finally, I want to choose a Cover Description from a drop-down list. All lists have already been created and work fine. The problem is....

In the red shaded cell L9 I want an equation that will look up a Cover Type (D9), Cover Description (D10) and a Hydrologic Soil Group (C9) and return a CN value from the table in the CN Values worksheet. If the soil group is A the the CN value should be 57. B returns 72, C returns 81, and D returns 86.

I would appreciate any help on this.

Try:
=INDEX('CN Values'!C$1:F$39,SUMPRODUCT(ROW('CN Values'!A$2:A$39),-('CN Values'!A$2:A$39=D9),-('CN Values'!B$2:B$39=D10)),MATCH(C9,'CN Values'!C$1:F$1,0))

You will find your spreadsheet much easier to work with without merged cells.

HTH

Problem solved. Thank you