Custom Calculation script that uses multiple dropdown lists

I have a rudimentary understanding of scripting; however, how do i assign numerical values to textual items in drop boxes to be used in variables for a calculation.

i.e. Dropdown1 includes (Dwarf = 10, Elf = 6, Human = 8); Dropdown2 includes (Bard = 6, Cleric = 6, Fighter = 10);

V1 = Dropdown1
V2 = Dropdown2

V3 = Level 

Total HP = V1 + [(V2+ "CON Modifier")V3]

I understand the basis of the script I just need assistiance on how to make the text in the dropdown correlate to a numerical variable.

Thank you for any assistance rendered.