Need help linking a formula to a drop-down - maybe

[stevenwiezorek]

Ill try and explain this the best I can. It doesn't seem like the most complicated thing but I just cant figure it out. What I'm trying to do is set up a formula of some sort that will be placed in Column "I" for the "Unit Price". The unit price is also affected by the "pier size" and the "Amount deeper or shallower"(basically if its negative or positive). So in the the case for Row 6, the pier size I selected was 18" and the depth was actually 0.60 deeper than expected(Unit Price ADD from right table), so that means my unit price would be $18.47. I am looking for something that will find the appropriate unit price for the two conditions. Sorry, I cannot link my actual file as I cannot download the software (work computer) to do so.

Any help is appreciated, thanks!