Scripting Question

Hopefully this is a simple solution, but I'm attempting to take the information from a drop-down field to calculate the field of a single-line to help automate the entries for our techs.

Basically if a tech selects

Drop-down1, 1st result, I want Field2 to populate with 100. If the tech selects Drop-down1, 2nd result then Field2 should be populated with 350, etc.

Thanks in advance,